The Messenger of Allah ﷺ said, "Whoever sends one blessing upon me, Allah will send ten blessings upon him in return."
حدثنا علي بن حجر أخبرنا إسمعيل بن جعفر عن العلاء بن عبد الرحمن عن أبيه
قال رسول الله ﷺ من صلى علي صلاة صلى الله عليه بها عشرا
No references are available.
Muslim also reported it in the book of Prayer, chapter on sending blessings upon the Prophet ﷺ after the tashahhud, hadith 408, from Ali bin Hujr, with the same chain.On this subject there are also narrations from Abdul-Rahman bin Awf [Ahmad 1/191, and Mustadrak of Hakim 1/550], Amir bin Rabia [Ibn Majah, hadith 907], Ammar [Bazzar (Kashf 4/47, hadith 3162, 3163)], Abu Talha [Nasai, hadith 1284, 1296], Anas [Nasai, hadith 1298], and Ubayy bin Kaab [to come, 2457].