The eminent Muslim scholar and renowned Da`iyah, Sheikh `Abdel Khaliq Hasan Ash-Shareef, states: “It should be clear that this is a controversial issue among Muslim jurists. Some Muslim scholars are of the opinion that touching the sexual organ with bare hands nullifies wudu’ based on the hadith narrated by Busrah bint Safwan that the Prophet (peace and blessings be upon him) said, “Whoever touches his sexual organ cannot pray until he performs ablution.” (Reported by Al-Bukhari) In the narration of Ahmad and An-Nasa’i, Busrah heard the Prophet saying, “Ablution is to be made by a person who touches his sexual organ.”
However, other Muslim jurists are of the opinion that touching the private parts does not nullify wudu’ based on the following Hadith, that touching the sexual organ does not nullify the ablution: “A man asked the Prophet (peace and blessings be upon him) if touching the penis necessitates performing ablution. The Prophet (peace and blessings be upon him) said: “No, it is just a part of you.” (Reported by “the five” (five scholars of Hadith).
Having read the above mentioned hadiths, we can say that if one touched his sexual organ while feeling with desire, then this nullifies wudu’. But if he touched his sexual organ without paying any attention to desire and while feeling that it is only part of his/her body, then this does not nullify wudu’.”