Sayyiduna Abu Hurairah (may Allah be pleased with him) narrates that the Messenger of Allah (peace and blessings be upon him) said: "Indeed, when a servant sleeps, Satan ties three knots upon him. Then, if he wakes up during the night and remembers Allah, one knot is untied; if he performs ablution, two knots are untied; then if he performs two units of prayer, all the knots are untied. Therefore, untie the knots of Satan, even if it is with just two units of prayer."
Hadith Referenceصحيح ابن خزيمه / جماع أبواب صلاة التطوع بالليل / 1132