Nafi' (may Allah have mercy on him) said that Sayyiduna Abdullah bin Umar (may Allah be pleased with them both) used to pray at night, two rak'ahs at a time, as much as was decreed for him. If he feared the arrival of the morning, he would pray one rak'ah, and that would be at the end of his prayer. Sayyiduna Abdullah bin Umar (may Allah be pleased with them both) would sit and say the salam in the two rak'ahs after which the witr came. Then he would say 'Allahu akbar' (Allah is the Greatest) and pray the witr. Nafi' (may Allah have mercy on him) said: Mu'adh al-Qari (may Allah have mercy on him) also used to do the same.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصلاة / 4796