10 times
((اللَّهُمَّ صَلِّ وَسَلِّمْ عَلَى نَبَيِّنَا مُحَمَّدٍ)) (عشرَ مرَّاتٍ).
Edition transliteration
Allaahumma salli wa sallim 'alaa Nabiyyinaa Muhammadin[ten times]
Meaning
O Allaah, send prayers and peace upon our Prophet Muhammad.’ [ten times]
Source and references
Hisn al-Muslim, entry 98.The reference is copied from the edition; separate editorial verification is not complete yet.
Source edition: Fortress of the Muslim. Open source ↗