Sahih Bukhari Volume 4, Book 61, Hadith 3567

حَدَّثَنَا عَبْدُ الأَعْلَى بْنُ حَمَّادٍ، حَدَّثَنَا يَزِيدُ بْنُ زُرَيْعٍ، حَدَّثَنَا سَعِيدٌ، عَنْ قَتَادَةَ، أَنَّ أَنَسًا ـ رضى الله عنه ـ حَدَّثَهُمْ أَنَّ رَسُولَ اللَّهِ صلى الله عليه وسلم كَانَ لاَ يَرْفَعُ يَدَيْهِ فِي شَىْءٍ مِنْ دُعَائِهِ، إِلاَّ فِي الاِسْتِسْقَاءِ، فَإِنَّهُ كَانَ يَرْفَعُ يَدَيْهِ حَتَّى يُرَى بَيَاضُ إِبْطَيْهِ‏.‏

Narrated By Anas : Allah's Apostle did not use to raise his hands in his invocations except in the Istisqa (i.e. invoking Allah for the rain) in which he used to raise his hands so high that one could see the whiteness of his armpits. (Note: It may be that Anas did not see the prophet (as) raising his hands but it has been narrated that the Prophet (as) used to raise his hands for invocations other than Istisqa.