Please clarify regarding offering the voluntary prayers before and after the obligatory prayers?
My viewpoint is that, as you love and hold affection for the Prophet, Muhammad, sallallaahu 'alayhi wa sallam, you must definitely follow his Sunnah. But some people regard it as next to obligation. For example, during Fajr prayer, people who come late to the prayer do not join the congregation and start offering Sunnah and some times the prayer of congregation ends. I think this is not correct. People should first offer the Farz prayers and then offer Sunnah because they will be questioned about the obligatory prayers on the Day Judgement.

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.

All those prayers which are performed other than the obligatory prayers are called an-Nawafil (supererogatory prayers).

The Nawafil are of two kinds:

1. The specific Nawafil prayers, which are performed before and after the obligatory prayers are, called as-Sunan ar-Rawatib.

As-Sunan ar-Rawatib are of two kinds:

Confirmed Sunan which consist of twelve Rak’ahs; two Rak’ahs before the Fajr prayer; four Rak’ahs before the Thuhr prayer and two after it; two Rak’ahs after the Maghrib prayer and two after the ‘Isha prayer.

The unconfirmed Sunan are four Rak’ahs before 'Asr, two Rak’ahs before Maghrib and two Rak’ahs before ‘Isha.

2. The supererogatory prayers other than as-Sunan ar-Rawatib are many; some are as follows:

a) Witr the most important voluntary prayer, its minimum number is one Rak’ah and the maximum is thirteen. The time of Witr prayer begins after the ‘Isha and lasts till dawn. When one performs Witr in thirteen Rak’ahs he has to perform it in sets of two Rak’ahs and one in the last Rak’ah.

b) Tahajjud prayer is also called Qiyam al-Layl (night prayer). The time of this prayer is the same as the time of Witr prayer.

c) Thuha prayer, the minimum Rak’ahs of this prayer is two and the maximum are eight. The time of this prayer begins fifteen minutes after sunrise and lasts until just before meridian time.

3. There are other voluntary prayers, which are recommended on certain occasions such as performing two Rak’ahs after making Wudu, two Rak’ahs for Istikhaarah, two Rak’ahs when one meets his new bride for the first time, two Rak’ahs for the prayer for a need (Salaatul-Haajah). The prayer for a need is performed when a person needs something from Allah. Though some scholars do not agree about this prayer for the lack of sound evidence.

4. There are other prayers, which are performed in-groups such as the ‘Eed prayers, prayer for rain, prayer of lunar and solar eclipse. Only two Rak’ahs are performed in all the above prayers.

5. There are some other Nawafil which are called general voluntary prayers. They are not restricted to a given time or number. They may be performed at any time except the time when performing non-obligatory prayers is prohibited or disliked.

The Prophet Muhammad said: "If the congregational prayer begins no other prayer should be performed". [Muslim and the four Imams of Sunan]

Many scholars deduce from this Hadith that initiating any voluntary prayer after the beginning of an obligatory prayer is undesirable; some scholars even believe that the above Hadeeth proves that initiating any voluntary prayer after the beginning of a congregational prayer is forbidden. We support the latter opinion since the words of Hadeeth indicate the meaning of prohibition according to the rules of Usool al-Fiqh (Fundamentals of Islamic jurisprudence).

Interrupting (abandoning) a voluntary prayer may be with Tasleem (saying Assalamu Alaykum –to end the prayer) before completing it or merely leaving it or doing any act, which normally annuls the prayer.

Allah knows best.