It is narrated from Sayyiduna al-Hasan bin Ali (may Allah be pleased with him) that the Messenger of Allah (peace and blessings be upon him) said: "Wherever you are, send blessings (salawat) upon me, for your blessings reach me."
Hadith Referenceالمعجم الكبير للطبراني / باب الحاء / 2716