Language:
كتاب المناقب
61  
Virtues and Merits of the Prophet (pbuh) and his Companions
(23)
Chapter: The description of the Prophet (saws)
(23)
باب صِفَةِ النَّبِيِّ صلى الله عليه وسلم
Sahih al-Bukhari 3565

Narrated Anas:

Allah's Messenger (ﷺ) 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. See Hadith No. 612 Vol. 5. and Hadith No. 807 & 808 Vol 2.)

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.‏ وَقَالَ أَبُو مُوسَى دَعَا النَّبِيُّ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ وَرَفَعَ يَدَيْهِ وَرَأَيْتُ بَيَاضَ إِبْطَيْهِ
Reference : Sahih al-Bukhari 3565
In-book reference : Book 61, Hadith 75
USC-MSA web (English) reference : Vol. 4, Book 56, Hadith 766
  (deprecated numbering scheme)