Is it permissible to pray with the ablution (wudu') performed for touching the Mushaf or reciting the Qur’an, and is it obligatory to renew the ablution for prayer if one performed the recommended ablution for sleep?

If you perform ablution (wudu') to touch the Qur'an, it is permissible for you to pray with that ablution. This is because touching the Qur'an requires ritual purity, and whoever performs ablution for an obligatory act may use that ablution for other acts for which ablution was not specifically performed. However, if you perform ablution for something for which purity is recommended, such as reciting the Qur'an without touching the Mushaf, or if you perform ablution before sleeping, scholars have differed regarding the permissibility of praying with that ablution. The Maliki and Shafi'i schools, and one opinion among the Hanbalis, hold that prayer with such ablution is invalid. The prevailing opinion among the Hanbalis, however, is that it is permissible to pray with such ablution. The most cautious and safest approach to absolve oneself of responsibility is to adopt the first view. Therefore, if you perform ablution for sleep and then wish to pray, perform ablution again with the intention of removing impurity or for prayer.