Answered by Shaykh Sohail Hanif, SunniPath Academy Teacher
Prayer: My friend fiddles with his private parts in prayer… Isn’t that just so wrong? What do I tell him?

Walaikum assalam wa rahmatullah,
Imam Muhammad ibn al-Hasan relates in his Mutawwa with his chain of narrators from Arqam ibn Shurhayl that he said to Abdullah ibn Mas’ud “I scratch my body while I’m praying causing me to touch my penis,” so the Prophet (Allah bless him and give him peace) replied, “It is just a part of you” [al-Ta’liq al-Mumajjad ala Muwatta al-Imam Muhammad, 1:218, Dar al-Qalam].
Ibn Mas’ud (Allah be pleased with him) said that, It is just a part of you’ implies that merely touching one’s private parts does not invalidate one’s ablution.
As concerns movements during the prayer, the general rule is that:
1. Slight movement is permissible (mubah) when done for a reason relating to the prayer, for example relieving a strong irritating itch, or to loosen cloths that stuck to one after raising from prostration.
2. If this was done for no particular reason then it is somewhat disliked.
3. If it is a major movement such that if an onlooker from afar were to see it they would think to themselves that this person was certainly not praying then it constitutes excessive movement and will invalidate the prayer.
4. If a slight movement is repeated several times for no particular reason then it constitutes fidgeting (abath) and is prohibitively disliked meaning that it is sinful and necessitates the prayer to be repeated. [al-Durr al-Mukhtar]
In general the prayer is described as the ascent of the believer’ (mi’raj al-mu’min). One in the presence of a king of this world would not fidget with themselves and certainly not with their private parts, so how much more someone in the presence of his Lord?
The abovementioned rules pertaining to moving during the prayer are to encourage one to remain still in one’s prayer so as to enable one’s heart to focus on the purpose of the prayer which is to humbly entreat the Divine.
[Faraz adds: thus, what your friend’ is doing is blameworthy, but not sinful, as such, advise him gently, with love to leave ]
And Allah alone gives success.
Sohail Hanif