Shaikh Ibn ul-‘Uthaymeen rahimahullah said:
“What is correct is that he raises his hands because that is authentic from Umar ibn al-Khattab radiallahu anhu [Reported by al-Bayhaqi (2/212) and he authenticated it]. And Umar ibn al-Khattab radiallahu anhu is one of the four guided Caliphs whose Sunnah is followed due to the order of the Prophet(ﷺ) [Reported by Abu Dawood no. 4604 and Tirmidhi no. 2676]. So he raises his hands.
However, how does he raise his hands?
Answer: The Scholars say he raises his hands to his chest and does not raise them a lot because this supplication is not a supplication of Ibtihaal [invocation] in which a person exaggerates in raising. Rather, this is a supplication of hoping. He spreads his hands and both palms towards the sky. This is what our companions say rahimahumullah.
What is apparent from the speech of the People of Knowledge is that he joins his hands together, one to the other. Like the situation of beggar who asks others to give him something. As for separating the hands and spacing them out, then I do not know an origin for it. Not in the Sunnah nor in the speech of the Scholars”
[Sharh Mumti’ (4/9)]
Shaikh Bakr Abu Zaid rahimahullah said:
“The position of general supplication which is called Masalah (asking) and it is also called dua. It is to raise the hands to the shoulders or the like, joining them together, spreading the palms towards the sky and the back of the hands to the earth. If he wishes, he can cover his face and the back of his hands can face the Qiblah. This form is general for when raising of the hands in supplication in general: in the qunut in witr, rain prayer, the times when raising the hands in the six places in Hajj, and other than that”
[Tasheehul-Duaa pg. 116-117]
Translated by
Faisal Ibn Abdul Qaadir Ibn Hassan
Abu Sulaymaan