Answered by Ustadh Salman Younas
Question: Is it sunna to renew my wudu right before sleeping? Even if I was already in a state of wudu?
It is recommended (mandub) to sleep in a state of purification. This is based on the statement of the Prophet (blessings and peace be upon him), “When you go to your bed, perform ablution like the ablution for prayer and then lie on your right side.” [Muslim]
It is also recommended to perform ablution after waking up from sleep as per the statement of the Prophet (blessings and peace be upon him), “Whoever sleeps let him perform ablution [afterwards].” [Ibn Majah]
It should be noted, however, that the recommendation to perform ablution after waking up from sleep relates to when one is not about to pray. If one needs to pray, then ablution would be obligatory if one slept in a manner nullifying ablution, namely a deep sleep without the rear being firmly seated.
[al-Shurunbulali, Imdad al-Fattah (81)]
Please also see: What are the Rewards of Sleeping in a State of Ritual Purity (Wudu)?
Checked & Approved by Shaykh Faraz Rabbani