Hisn al-Muslim
The excellence of asking for Allah's blessings upon the Prophet pbuh — Du'a 4
وَقَالَ صلى الله عليه وسلم:((إِنَّ لِلَّهِ مَلاَئِكَةً سَيَّاحِينَ فِي الأَرضِ يُبَلِّغُونِي مِن أُمَّتِي السَّلاَمَ)).
English meaning
The Prophet [PBUH] said:'Indeed Allah has angels who roam the earth and they convey to me the greetings (or prayers of peace) of my 'Ummah (nation).