Reference : Hisn al-Muslim 98

اللَّهُمَّ صَلِّ وَ سَلِّمْ عَلَى نَبِيِّنَا مُحَمَّدٍ
(عشر مرات)
Allāhumma ṣalli wa sallim `alā nabiyyinā Muḥammad.

O Allah, we ask for your peace and blessings upon our Prophet Muhammad. 
(Recite ten times in Arabic.)

Reference:
The Prophet (ﷺ) said: "Who recites blessings upon me ten times in the 
morning and ten times in the evening will obtain my intercession on the Day 
of Resurrection." At-Tabarani reported this Hadith together with two chains 
of transmission. One of them is reliable (Jayyid). See Haythami's 
Majma'uz-Zawa'id 10/120, and Al-Albani's Sahihut-Targhib wat-Tarhib 1/273.

Chapter: In the morning and evening