After being free from istinja is it necessary to wash the penis with hand or pouring water onto it is enough?
بسم الله الرحمن الرحيم
(Fatwa: 425/366/B=3/1439)
Only pouring water shall also suffice, but sometimes urine drops remain in private part of a weak person hence he should press by hand so that complete taharah is achieved.
Allah knows Best!
Darul Ifta,
Darul Uloom Deoband