Is invoking peace and blessings upon the Prophet (peace be upon him) after saying the Du`a' (supplications) at the end of the obligatory Salah (Prayer) a Sunnah (supererogatory act of worship following the example of the Prophet) or Bid`ah (innovation in religion)?
Invoking peace and blessings upon the Prophet (peace be upon him) after the Tashahhud (a recitation in the sitting position in the second/ last unit of Prayer) in every Salah is lawful, whether the Salah is obligatory or supererogatory. It is also lawful to say it before the beginning of a Du`a' and after praising Allah at any time. This is one of the reasons that Du`a' is responded to, (Part No. 7; Page No. 121) according to the Hadith that was authentically reported by
Fadalah ibn `Ubayd (may Allah be pleased with him), who said,
The Messenger of Allah (peace be upon him) heard someone supplicating after his Salah, without praising Allah and without invoking peace and blessings upon the Prophet (peace be upon him). The Messenger of Allah (peace be upon him) said, "This man rushed." Then he called him and said to him or to other than him, "When any one of you has performed Salah, let them praise Allah and glorify Him, invoke peace and blessings upon the Prophet, and then supplicate Allah for whatever they wish."
May Allah grant us success. May peace and blessings be upon our Prophet Muhammad, his family, and Companions.