Anas said the Prophet (ﷺ) was not accustomed to raise his hands in any supplication he made except when praying for rain. He would then raise them high enough for the whiteness under his armpits to be visible. (Bukhari and Muslim.)

وَعَنْ أَنَسٍ قَالَ: كَانَ النَّبِيُّ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ لَا يَرْفَعُ يَدَيْهِ فِي شَيْءٍ مِنْ دُعَائِهِ إِلَّا فِي الِاسْتِسْقَاءِ فَإِنَّهُ يَرْفَعُ حَتَّى يرى بَيَاض إبطَيْهِ