1-The arranged sunnahs* he (pbuh) said: (in no way does a muslim slave pray to allah twelve rak’as (units of prayer) per day, except (that) allah builds a house for him in paradise, or (that) a house is built for him in paradise). narrated by muslim.
- These are as follows: four rak’as before athuhr (noon) prayer and two after it, two rak’as after al-maghreb (sunset) prayer, two rak’as after al-isha’ (evening) prayer and two rak’as before al-fajr (dawn) prayer.
- my beloved brother: don’t you yearn for a house in paradise? preserve this prophetic advice and pray twelve rak’as other than the obligatory prayers.
1-Ad-duha (forenoon) prayer:
it is equal to  sadaqas (charitable deeds). since, man’s body consists of  bones, therefore, each bone of them needs a sadaqa daily to be a sort of thanks (to allah) for this blessing. instead of all of this, two rak’as in the forenoon are sufficient.
its' two fruits: as reported in the authentic narrations of muslim, who quoted abu-dhar as saying that the prophet (pbuh) said: (every morning, there becomes a sadaqa for every joint in anyone of you. every glorification is a sadaqa, commanding beneficence is a sadaqa, forbidding malfeasance is a sadaqa and instead of this, two rak’as performed in the forenoon are sufficient).
abu-huraira – may allah be pleased with him – was quoted as saying: (my fellow (pbuh) enjoined me concerning fasting three days every month, the two rak’as of ad-duha and performing al-wetr prayer before i go to bed). agreed upon.
its time: it starts 15 minutes (quarter of an hour) after sunrise, until quarter of an hour before athuhr (noon) prayer.
the best time to perform it: when the heat of the sun intensifies.
its number: its minimum number is two rak’as.
its maximum (number): eight rak’as and it has been said that there is no limit for its maximum.
2- the sunnah of al-asr (afternoon) prayer:
he (pbuh) said: (may allah have mercy on this who performs four rak’as before al-asr (afternoon) prayer). narrated by abu-dawoud and at-termithi.
3- the sunnah of al-maghreb (sunset) prayer:
he (pbuh) said: (perform prayer before al-maghreb, in the third time he said: for this who wants). narrated by al-bukhari.
4- the sunnah of al-isha’ (evening) prayer:
he (pbuh) said: (between every two athans (calls to prayer) there is a prayer; between every two athans (calls to prayer) there is a prayer, between every two athans (calls to prayer) there is a prayer, in the third he said: for this who wants). agreed upon.
- an-nawawi said: the meaning of the two athans: the athan (call to prayer) and al-iqamah (the call to start performing prayer).
* the arranged sunnahs = the supererogatory prayers performed
with the daily five obligatory prayers and according to their order.