«كان إذا كان في وتر من صلاته لم ينهض حتى يستوي قاعدا»
It was the practice of the Prophet (peace and blessings be upon him):
"When he (peace and blessings be upon him) was in an odd-numbered rak'ah of his prayer, he would not stand up until he had sat up fully."
Hadith Referenceصحیح الجامع الصغیر / حرف الكاف / 4773