Nafi' said: Sayyiduna Ibn Umar (may Allah be pleased with them both) would keep the night alive with prayer, then he would say: "O Nafi', has the pre-dawn time come?" I would say: No, so he would return to the prayer. Then he would say: "O Nafi', has the pre-dawn time come?" and I would say: Yes. Then he would sit and keep seeking forgiveness and supplicating until morning came.
Hadith Referenceالمعجم الكبير للطبراني / باب العين / 12987