The base principle in supplication is that the servant be in a state of humility and humbleness while he beseeches his Lord, The Almighty, and Exalted be He; and the raising of the hands when supplication was reported for the sake of demonstrating this humility and humbleness. The Prophet ﷺ stated that Allah [would be] ashamed [if] the servant raised his hands in supplication, and He [were] to respond to him without granting his request; like what is reported according to Abu Dawud. In this hadeeth, Anas ibn Maalik(may Allah be pleased with him) mentions that the Prophet ﷺ did not raise his hands in any sort of supplication, except when he was invoking Allah for rain; and that when he did this, he would raise his hands in supplication until the whiteness of his armpits appeared. The intended [conveyance of meaning] here is that the Prophet ﷺ did not exert himself in raising his hands to the degree that the whiteness of his armpits would be seen, except during al-Istisqaa’ - which is invoking Allah for rain. Otherwise, it has been mentioned in many reports and narrations that the Prophet ﷺ would raise his hands in many supplications other than the istisqaa’..