مسائل المنتخبه (Articles Of Islamic Acts) - الخوئي، السيد أبوالقاسم - الصفحة ٢٤٦ - ORDERS REGARDING THINGS WHICH INVALIDATE PRAYERS

he places his forehead on the ground withthe intention of thanksgiving. However, it is better that he should say Shukran lillah or Al-afv ١٠٠ times or thrice or once only and it is also recommended that whenever aperson is favoured with a blessing or gets rid of a hardship he should perform a prostration of thanksgiving.

SALAWAT (GREETING) ON THE HOLY PROPHET
١١٣٣. It is recommended that whenever a person hears or utters the sacred name of the holy Prophet of Islam (for example Muhammad or Ahmad), or his title (for example, Mustafa) or his patronymic (for example, Abul Qasim) he should say. "Alahumma salli ala Muhommadin wa Ale Muhammad" even though he may be offering prayers at thattime.
١١٣٤. It is recommended that while writing the sacred name of the holy Prophet greeting be written for him. And it is also preferable that whenever his name is mentioned greeting be sent on him.

ORDERS REGARDING THINGS WHICH INVALIDATE PRAYERS
١١٣٥. Twelve things make prayers void and they are called mubtilat.First: If while offering prayers one of the necessary conditions of prayers ceases to exist. For example, if the person concerned comes to know hat the dress with which he has covered himself is an usurped one.Second: While offering prayers a person is faced, intentionally or by mistake or owing to helplessness, with a situation which makes his ablutions or bath (Ghusl) void - for example, if urine is discharged from his body. However, as regards a person who cannot control his faeces or urine, his prayers will not become void if he acts according to the instructions detailed earlier in