«حَتَّى انْتَهَى إِلَى مَغَارَةٍ فَانْسَابَ فِيهَا عَلَى غَرَارَةٍ»
He reached a cave and slipped into it, unaware of being followed.
Maghārah means a cave; insāba conveys slipping or gliding inward. The expression ʿalā gharārah suggests unawareness or heedlessness of the follower.
The man who commanded a crowd's attention is now in a secluded place. The change of setting prepares a change in the reader's understanding.