Sahih al-Bukhari 991
Sahih al-Bukhari · Book 14: Witr Prayer · What is said regarding the Witr prayer
وَعَنْ نَافِعٍ ، أَنَّ عَبْدَ اللَّهِ بْنَ عُمَرَ ، كَانَ يُسَلِّمُ بَيْنَ الرَّكْعَةِ وَالرَّكْعَتَيْنِ فِي الْوِتْرِ، حَتَّى يَأْمُرَ بِبَعْضِ حَاجَتِهِ .
Nafi` told that `Abdullah bin `Umar used to say Taslim between (the first) two Rak`at and (the third) odd one in the Witr prayer, when he wanted to attend to a certain matter (during that interval between the Rak`at).