Sayyiduna Ibn Abbas (may Allah be pleased with them both) narrates that the Messenger of Allah (peace and blessings be upon him) used to pray thirteen rak‘ahs (units) of (the night prayer) Tahajjud at night.
Hadith Referenceصحيح ابن خزيمه / جماع أبواب صلاة التطوع بالليل / 1164