عَنْ عَبْدِ اللَّهِ بْنِ عَمْرٍو رَضِيَ اللَّهُ عَنْهُمَا يَقُولُ مَنْ صَلَّى عَلَى رَسُولِ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَآلِهِ وَسَلَّمَ صَلَاةً صَلَّى اللَّهُ عَلَيْهِ وَمَلَائِكَتُهُ سَبْعِينَ صَلَاةً فَلْيُقِلَّ عَبْدٌ مِنْ ذَلِكَ أَوْ لِيُكْثِرْ
Narrated from Sayyiduna Abdullah bin Amr (may Allah be pleased with him), he says: Whoever sends blessings upon the Messenger of Allah (peace and blessings be upon him) once, Allah Almighty will send seventy mercies upon him, and His angels will supplicate for mercy for him seventy times. Now it is up to the servant whether he sends blessings less or more.