Sahih Muslim
Characteristics of The Hypocrites And Rulings Concerning Them
كتاب صفات المنافقين وأحكامهم
Ibn Umar reported Allah's Apostle (ﷺ) as saying
The similitude of a hypocrite is that of a sheep which roams aimlessly between two flocks. She goes to one at one time and to the other at another time.
Ibn Umar reported Allah's Apostle (ﷺ) saying like this but with this change of words
" She sometimes finds a way in one flock and then in another flock."