Ruling 1091. After completing tashahhud of the last rakʿah of the prayer, it is recommended that while one is sitting and his body is still, he should say:

اَلسَّلَامُ عَلَیْكَ أَيُّــهَا النَّبِيُّ وَ رَحْمَةُ اللهِ وَ بَـرَکَاتُهُ

assalāmu ʿalayka ayyuhan nabiyyu wa raḥmatul lāhi wa barakātuh

And after that, he must say:

اَلسَّلَامُ عَلَیْكُمْ

assalāmu ʿalaykum

And the recommended precaution is that [after saying assalāmu ʿalaykum,] one adds the sentence:

وَ رَحْمَةُ اللهِ وَ بَـرَکَاتُهُ

wa raḥmatul lāhi wa barakātuh

Or [i.e. instead of saying assalāmu ʿalaykum], one must say:

اَلسَّلَامُ عَلَیْنَا وَ عَلَىٰ عِبَادِ اللهِ الصَّالِحِینَ

assalāmu ʿalaynā wa ʿalā ʿibādil lāhiṣ ṣāliḥīn

However, if he says this, then the obligatory precaution is that he must also say after it:

اَلسَّلَامُ عَلَیْكُمْ

assalāmu ʿalaykum

Ruling 1092. If a person forgets the salām of the prayer and remembers it before the form of the prayer has broken up, and if he has neither intentionally nor inadvertently done something that would invalidate his prayer – such as turning his back to qibla – then he must say the salām and his prayer is valid.

Ruling 1093. If a person forgets the salām of the prayer and remembers it after the form of the prayer has broken up, or if he has intentionally or inadvertently done something that would invalidate his prayer – such as turning his back to qibla – then his prayer is valid.