Prayer has great and numerous virtues, some of which are the following:
1) Prayer forbids the person from falling into the abyss of immorality and wrongdoing. Allah, the Exalted, Says (what means): {Recite [O Muhammad] what has been revealed to you of the Book and establish prayer. Indeed, prayer prohibits immorality and wrongdoing, and the remembrance of Allah is Greater. And Allah knows that which you do.} [Quran 29:45]
2) It is the best righteous deed after professing the two testimonies of faith. ‘Adullah ibn Mas‘ood said, "I asked the Prophet 'What is the best deed?' He said: 'Performing prayer in its due time.' I further asked, 'Then what?' He replied: 'Dutifulness toward parents.' I further asked, 'Then what?' He replied: 'Performing Jihad in the Cause of Allah The Exalted.'" [Al-Bukhari and Muslim]
3) Prayer wipes away sins. Jabir reported that the Prophet said: "The similitude of the five daily prayers is like a great overflowing river running by the door of one of you, in which he washes himself five times a day." [Muslim]
4) Prayer expiates sins. Abu Hurayrah reported that the Prophet said: "The five daily (obligatory) prayers, and Friday (prayer) to the next Friday (prayer), and the fasting of Ramadan to the next Ramadan, are expiation of the sins committed in the interval between them, so long as major sins are avoided." [Muslim]
5) Prayer is a light for the praying person in this worldly life and the Hereafter. ‘Abdullah ibn ‘Umar narrated that the Prophet said:
Whoever keeps on performing prayer (on its due time), it will be a light, evidence, and salvation for him on the Day of Judgment. But, for whoever fails to do so, it will not be a light, evidence, or salvation; and on the Day of Judgment he will be with Qaroon, Fir‘awn, Haman, and Ubayy ibn Khalaf. [Ahmad]
Abu Malik Al-Ash‘ari reported that the Prophet said: "Prayer is light." [Muslim]
Moreover, Buraydah narrated that the Prophet said: "Convey glad tidings to those who walk to the mosques in the darkness of a perfect (and full) light on the Day of Judgment." [Abu Dawood, At-Tirmithi and Al-Albani classified as authentic]
6) As a reward for performing the prayer, Allah, the Exalted, raises the person's degree in Paradise and obliterates his sins. Thawban, the freed slave of the Prophet reported that he said: "Make frequent prostrations to Allah, the Exalted, for you will not make one prostration except that Allah Almighty raises you to a higher degree and removes a sin from your record because of it." [Muslim]
7) It is one of the greatest reasons for entering Paradise in the company of the Prophet . Rabee‘ah ibn Ka‘b Al-Aslami said, "I was staying with the Prophet one night and I brought him water (for ablution) and whatever he needed. He said to me: 'Ask (anything you like).' I said, 'I ask for your company in Paradise.' He said: 'Do you ask for anything else besides it?' I replied, 'No, that is all (I require).' He said: 'Then, help me in fulfilling your request by devoting yourself often to prostration.'" [Muslim]
8) When the person walks to the mosque with the intention of performing the prayer, he gains rewards, his sins are forgiven, and his degree in Paradise is elevated. Ahu Hurayrah narrated that the Prophet said:
He who purifies himself (performs ablution) in his house and then walks to one of the Houses of Allah (mosque) to perform an obligatory prayer of those ordained by Allah Almighty, one step of his will wipe away a sin and another step will raise his degree in Paradise. [Muslim]
Another hadeeth reads:
If any one of you performs ablution perfectly and thoroughly, and goes out for prayer, he does not take a step by his right foot but Allah records a good deed for him, and he does not take a step with his left foot but Allah obliterates one sin from him… [Abu Dawood]
9) Good accommodation in Paradise is prepared for the Muslim every time he goes to the mosque in the morning or in the evening. Ahu Hurayrah narrated that the Prophet said: "He who goes to the mosque at dawn or dusk (for the congregational prayers), Allah prepares a hospitable abode for him in Paradise, every time he does so." [Al-Bukhari and Muslim]
10) Allah, the Exalted, forgives the sins that are committed between two successive prayers. ‘Uthman said:
I heard the Messenger of Allah say: "If a Muslim performs ablution thoroughly and offers prayer, he will be forgiven for all the sins that are committed between this prayer and the next one." [Muslim]
11) When one performs a prayer, the sins that are committed prior to performing this prayer are forgiven. ‘Uthman ibn ‘Affan reported that he heard the Messenger of Allah say:
When the time for a prescribed prayer is due and a Muslim performs ablution for it thoroughly, observes khushoo‘ (concentration, submissiveness) in it and performs its bowing and prostration properly, this prayer will be expiation for the sins committed before it, so long as he does not commit major sins, and this applies for every prayer. [Muslim].
12) When the person performs the prayer, the angels supplicate Allah, the Exalted, to forgive him and have mercy upon him as long as he remains in his place of prayer. He is considered in prayer as long as he is waiting for the prayer and it is only the prayer that prevents him from leaving the mosque. Ahu Hurayrah narrated that the Prophet said:
The reward for a prayer that is performed by a person in congregation is more than twenty times greater than that of the prayer performed in one's house or shop. When one performs ablution perfectly and then proceeds to the mosque with the sole intention of performing prayer, and nothing urges him to proceed to the mosque except the prayer, for every step he takes towards the mosque, he is upgraded one degree in reward and one of his sins is eliminated until he enters the mosque. When he enters the mosque, he is considered as performing prayer as long as it is the prayer which prevents him (from leaving the mosque); and the angels keep on supplicating Allah for him as long as he remains in his place of prayer. They (the angels) say: "O Allah, have mercy on him; O Allah, forgive his sins, O Allah, accept his repentance." This will continue as long as he does not invalidate his ablution." [Al-Bukhari and Muslim]
13) Waiting for the prayer is considered ribat (a type of Jihad) for the Cause of Allah, the Exalted. Ahu Hurayrah narrated that the Prophet said: "Shall I not tell you something by which Allah erases sins and elevates ranks (in Paradise)?” The Companions said; "Certainly, O Messenger of Allah." He said: "Performing ablution thoroughly even if it is hard to, walking with more paces to the mosque, and waiting for a prayer after a prayer; indeed that is ar-ribat, indeed that is ar-ribat ." [Muslim]
14) Whoever goes to the mosque with the intention of performing the prayer, will obtain the rewards of a pilgrim in the state of ihram (ritual consecration). Abu Umamah reported that the Prophet said:
If anyone goes out from his house after having performed ablution so as to offer the prescribed prayer in congregation (in the mosque), his reward will be like that of a pilgrim who is in a state of ihram. Whoever goes out to offer Dhuha prayer, and takes the trouble for this purpose, will obtain the reward like that of a person who performs ‘Umrah. And a prayer followed by a prayer with no worldly talk during the gap between them will be recorded in ‘Illiyyeen (seventh heaven). [Abu Dawood and Al-Albani considered as good]
15) If someone who is a regular observer of congregational prayers hastens to the mosque to perform the prayer, but finds the prayer has already finished, he will gain the same rewards as if he had performed it with them in congregation. Ahu Hurayrah narrated that the Prophet said:
Whoever performs ablution perfectly, and then goes to the mosque and finds that the people had finished the prayer (in congregation), Allah will give him a reward like one who prayed in congregation and attended it in full; the reward of those who prayed in congregation will not be curtailed. [Abu Dawood and Al-Albani classified as authentic]
16) When one performs ablution and goes to the mosque with the intention of performing the prayer, he is considered performing the prayer until he comes back from the mosque. His going to and coming back from the mosque will be recorded for him. Abu Hurayrah narrated that the Prophet said:
If any of you performs ablution in his house and then goes to the mosque, he is considered in prayer until he returns; (therefore,) he should not intertwine his fingers while staying in the mosque as he is [considered to be] in prayer.
He illustrated this by interlacing the fingers of both his hands. [Ibn Khuzaymah, Al-Hakim; Ath-Thahabi: authentic] Abu Hurayrah also narrated in a marfoo' (the narration attributed directly to the the Prophet ) hadeeth that the Prophet said: "… since one departs his house, walking to my mosque, his steps are counted as one is recorded as a reward and the other expiates a sin." [Ibn Hibban, An-Nasa’i and Al-Albani classified as authentic]