Sunan Abi Dawud, Hadith 1482 ⓘ
Narrated Anas ibn Malik: I saw the Messenger of Allah supplicating Allah in this manner with the palms of his hands and also with their backs upwards.
حَدَّثَنَا عُقْبَةُ بْنُ مُكْرَمٍ، حَدَّثَنَا سَلْمُ بْنُ قُتَيْبَةَ، عَنْ عُمَرَ بْنِ نَبْهَانَ، عَنْ قَتَادَةَ، عَنْ أَنَسِ بْنِ مَالِكٍ، قَالَ رَأَيْتُ رَسُولَ اللَّهِ صلى الله عليه وسلم يَدْعُو هَكَذَا بِبَاطِنِ كَفَّيْهِ وَظَاهِرِهِمَا .
also referenced under: Hadith 1487 (DarusSalam) & Book 8, Hadith 1482 (USC-MSA)