وَقَالَ صلى الله عليه وسلم:((إِنَّ لِلَّهِ مَلاَئِكَةً سَيَّاحِينَ فِي الْأَرْضِ يُبَلِّغُونِي مِنْ أُمَّتِي السَّلاَمَ)).
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).
An-Nasa'i, Al-Hakim 2/421. Al-Albani graded it authentic in Sahih An-Nasa'i 1/274.