Q: Someone from Al-Sharqiyyah governorate, the Arab Republic of Egypt, asks: If a man touches his private parts or the private parts of one of his children, or if the mother touches the private parts of one of her children, must they renew their Wudu’ (ablution)?
A: Yes, if a man touches the private parts without a barrier; namely, the skin of the hand touches the skin of the private part, penis or anus, his ablution will be nullified. Similarly, if a woman touches her private parts or the private parts of her children, her ablution will be nullified.
The Prophet (peace be upon him) stated: He who touches his penis should perform ablution. He (peace be upon him) also stated: He who touches his private parts without a barrier should perform ablution.
Therefore, if someone touches their private parts without a barrier, their ablution will be nullified. But if they do this over a barrier of clothing, loincloth or pants, there is nothing wrong with this and their Wudu’ remains valid. What invalidates Wudu’ is the bare hand touching the skin of the private parts without a barrier between them.
Source for above: http://alifta.net/ – Fatwas of Nur `Ala Al-Darb
Abu Hurayrah (radhi-yAllaahu ‘anhu) said: Rasoolullaah (sal-Allaahu ‘alayhe wa sallam) said:
«If one of you touches his penis and there is no veil between him and it nor any cover, then wudhoo has become obligatory for him.» [al-Haakim (1/138) and others]. (al-Albaanee says: hadeeth Saheeh.)