Matthew Poole and continuators on Exodus 4:18

18 And Moses went and returned to Jethro his father-in-law, and said unto him, Let me go, I pray thee, and return unto my brethren which are in Egypt, and see whether they be yet alive. And Jethro said to Moses, Go in peace.

He pretends only a visit, and so indeed it was, and that no very long one neither: He knew that he should certainly return to this place, and there meet with his Father-in-law. So that he did not deceive him nor intended to do so, though he thought fit to conceal from him the errand, upon which God sent him, lest his Father or Wife should attempt to hinder or discourage him from so difficult and dangerous an enterprize. Moses shews here a rare example as well of modesty and humility, that such glorious and familiar converse with God and the high calling to which God had advanced him did neither make him forget the civility and duty which he owed to his Father, nor make him break forth into publick and vainglorious boasting of such a priviledge; as also of his piety and prudence, that he avoided all occasions and temptations to disobedience to Gods command.