Matthew Poole and continuators on Genesis 21:9

9 And Sarah saw the son of Hagar the Egyptian, which she had born unto Abraham, mocking :

Signifying either by words or gestures his contempt of Isaac, and his derision of all that magnificence then shewed towards his younger Brother: and this carriage proceeding from a most envious and malitious disposition, and being a sufficient indication of further mischief intended to him, if ever he should have opportunity, it is no wonder it is called persecution, Gal. 4. 29. Although the Hebrew word may be rendred beating him, as it is used 2 Sam. 2. 14.