Conveying peace and blessings on the Prophet is prescribed at the beginning of a Du`a' along with praising Allah; due to the Hadith narrated on the authority of
Fadalah ibn `Ubayd that is mentioned in this regard, in addition to Allah's command to generally convey peace and blessings upon his Prophet by saying (Exalted be He),
Allâh sends His Salât (Graces, Honours, Blessings, Mercy) on the Prophet (Muhammad صلى الله عليه وسلم), and also His angels (ask Allâh to bless and forgive him).
However, conveying peace and blessings on the Prophets is one of the reasons of answering the Du`a', but not a condition for it, and the Hadith saying,
Du`a' remains suspended between the earth and the Heaven until the person supplicating conveys peace and blessings on the Prophet (peace be upon him)
is a weak Hadith that does not stand as proof.May Allah grant us success. May peace and blessings be upon our Prophet Muhammad, his family, and Companions.