Sahih Bukhari · Hadith 991

وعن نافع، أن عبد الله بن عمر، كان يسلم بين الركعة والركعتين في الوتر، حتى يأمر ببعض حاجته‏.‏

Nafi' told that 'Abdullah bin 'Umar used to say Taslim between (the first) two Rakat and (the third) odd one in the Witr prayer, when he wanted to attend to a certain matter (during that interval between the Rakat).

Gradings are classical jarḥ-wa-taʿdīl, name-matched to a rijāl index (not individually re-verified).