1. What is the exact reward for praying all five prayers on time with all the Sunan Rawatib -and can you please tell me exactly how many Rak'ahs there are after each prayer
2. What is the reward for voluntary fasting?
3. What is the reward for learning Quran by heart?

All perfect praise be to Allah, The Lord of the Worlds. I testify that there is none worthy of worship except Allah, and that Muhammad is His slave and Messenger.

The prayer is the second most important pillar of Islam after the Shahaadatayn (The Two Testimonies of Faith). There is no doubt that preserving the prayer (offering obligatory prayers without neglect) is a sign of true belief. Whoever preserves the prayer will enter paradise, as the Prophet illustrated.

Ibn Majah and others reported that Abu Qatada narrated that the Prophet   said: “Allah, The Most High, said: “I prescribed five prayers on your Ummah (nation) and my pact is that whoever performs them at their due time, I will indeed admit him to Paradise, and whoever does not perform them, he has no pact with me.” Al-Albaani classified this Hadeeth as authentic in Al-Silsila As-Saheehah.

As regards supererogatory prayers, they are of two kinds:

Confirmed supererogatory prayers:

These are 12 Rak'ahs, their numbers and reward were mentioned in the Hadeeth narrated by Um Habeebah that the Prophet said:

“Whoever prays 12 Rak'ahs in 24 hours, a house in Paradise will be built for him: 4 Rak'ahs before Thuhr; 2 Rak'ahs after Thuhr; 2 Rak'ahs after Magrib; 2 Rak'ahs after ‘Isha; and 2 Rak'ahs before Fajr prayer.” [Al-Thirmithi]

Not confirmed supererogatory prayers: 2 Rak'ahs after Thuhr after performing the 2 Rak'ahs mentioned in the previous Hadeeth, and 4 Rak'ahs before ‘Asr, 2 Rak'ahs before Magrib, and 2 Rak'ahs before ‘Isha.

We draw the attention of the questioner to the fact that the 4 Rak'ahs before Thuhr and before ‘Asr should be performed in two's, as the Prophet said: “The prayer of the day and night are in two's.” [Ibn Hibbaan and ad-Daarimi; and Ibn Khuzaymah classified it as an authentic Hadeeth]

With regard to the reward of voluntary fasting, you have to know that the reward of fasting is great whether it is obligatory or voluntary. The Prophet said: “Your Lord is saying that every good deed is multiplied tenfold to 700 times, and fasting is observed for my sake and I will reward for it, and fasting is a protection from Hellfire.” [Al-Bukhari]

The meaning of this Hadeeth applies to obligatory and voluntary fasting.

Besides, many Ahadeeth were reported about voluntarily fasting during some specific days of the year.

Muslim reported in his Saheeh that “the Prophet was asked about fasting on the day of ‘Arafat and he replied: “I seek from Allah that fasting on the day of 'Arafah may atone for the sins of the preceding and the coming years.”

Fasting three days of each month is also very rewarding.

An-Nassa'i and others reported that Abu Thar narrated that the Prophet said: “Whoever fasts three days in each month, it is as if he fasted for the whole year.”

The excellence of performing voluntary acts of worship in general, whether it is prayers, fasting, or Sadaqah (alms), is great as Allah says in a Qudsi Hadeeth: “My slave keeps getting closer to Me through performing Nawaafil (supererogatory prayers), till I love him, then I become his sense of hearing with which he hears, and his sense of sight with which he sees, and his hand with which he grips, and his leg with which he walks; and if he asks Me, I will give him, and if he asks My protection (Refuge), I will protect him (i.e. give him My Refuge).” [Al-Bukhari and narrated by Abu Hurayrah.]

With regard to memorizing the Quran, Al-Haakim reported in Al-Mustadrak that Buraydah narrated that the Prophet said: “Whoever reads the Quran, memorizes it, and acts upon it, on the Day of Judgment, he will be clad (by angels) with a crown of light, its light is like the sun-light and his parents will be clad with two garments better than the whole world, so they would ask: “What action did we do to deserve this? " They will be told: "Because your son learnt the Quran.” It is said that this Hadeeth is authentic according to the conditions set by Muslim.

Abu Daawood and At-Thirmithi (and the wording is At-Thirmithi’s) reported that the Prophet said: “On The Day of Judgment, it will be said to the person who memorizes the Quran by heart, recite and go higher and higher, and recite as you were reciting in the worldly life. Indeed your status is as the last verse you read.”

For more benefit, please refer to Fataawa 378463, 182151, 86938, and 108251.

Allah knows best.