The ruling on one who prays witr at the beginning of the night and wishes to pray tahajjud at its end

This is a message we received from a listener in Riyadh (A. A. M. M). He says: My question is about the witr prayer. If I pray witr after 'Isha' before I sleep, out of fear that I will not be able to get up at the end of the night, and then I do get up at the end of the night and want to pray, is it permissible for me to do so and pray witr at the end, or not?
Answer: If a person prays witr at the beginning of the night as a precaution, that is correct and good. The Prophet (peace and blessings be upon him) advised Abu al-Darda' and Abu Hurayrah to pray witr at the beginning of the night. Some scholars said: He advised them to do so because they are occupied with knowledge at the beginning of the night, and it is difficult for them to get up at the end of the night. So if a person prays witr at the beginning of the night, and then Allah makes it easy for him to get up at the end of the night, he should pray whatever number of rak'ahs is easy for him, without praying witr, and he should be content with the first witr. This is because the Prophet (peace and blessings be upon him) said: So he should pray two rak'ahs, or four rak'ahs, or six rak'ahs, or more, without witr, at the end of the night. There is no blame in that, and there is nothing wrong with it. One is only advised to delay witr to the end of the night if he does not pray witr at the beginning of the night, and it is easy for him to get up at the end of the night. In that case, he is advised to make his witr at the end of the night if it is easy for him to do so, because the end of the night is better. So if Allah makes it easy for a servant to pray witr at the end of the night, that is better. But if he fears and worries that he will not get up at the end of the night, he should take the cautious approach and pray witr at the beginning of the night. And if Allah grants him the ability to get up at the end of the night, he should pray whatever is easy for him without witr, as came in the Sunnah from the Messenger (peace and blessings be upon him). It is established from 'A'ishah (may Allah be pleased with her): to make it clear to people that praying after witr is permissible, and there is no blame in it. Yes.