(Imām Bukhārī narrates): Muhammad bin Bashshar narrated the hadith to us, he said: Yahya and Ibn Adi narrated the hadith to us, from Sa'id, from Qatadah, from Hazrat Anas bin Malik (Allāh be pleased with him), he narrated that
the Prophet ﷺ did not raise his hands in any supplication except the prayer of Istisqa, and he ﷺ would raise his hands (to such an extent) that the whiteness of his armpits could be seen.
حَدَّثَنَا مُحَمَّدُ بْنُ بَشَّارٍ حَدَّثَنَا يَحْيَى وَابْنُ أَبِي عَدِيٍّ عَنْ سَعِيدٍ عَنْ قَتَادَةَ عَنْ أَنَسِ بْنِ مَالِكٍ قَالَ كَانَ النَّبِيُّ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ لَا يَرْفَعُ يَدَيْهِ فِي شَيْءٍ مِنْ دُعَائِهِ إِلَّا فِي الِاسْتِسْقَاءِ وَإِنَّهُ يَرْفَعُ حَتَّى يُرَى بَيَاضُ إِبْطَيْهِ
Reference: Sahih Al Bukhari 1031