Is it obligatory to repeat ablution after touching the penis with the left index finger while drying the body with a towel after performing ghusl for janabah, given the uncertainty as to whether the touch was with a barrier or not?

The predominant view is that touching the male organ directly with the hand invalidates ablution (wudu'), based on the hadith (definition) of Busra bint Safwan: "Whoever touches his male organ should perform ablution." However, touching it from behind a barrier does not invalidate ablution. If one doubts whether their ablution has been invalidated, the original state of purity remains, in accordance with the principle that certainty is not removed by doubt, and based on the hadith: "He should not leave (his prayer) until he hears a sound or perceives a smell."