Adam Clarke on Deuteronomy 33:16

The good will of him that dwelt in the bush - The favor of him who appeared in the burning bush on Mount Sinai, who there, in his good will - mere love and compassion, took Israel to be his people; and who has preserved and will preserve, in tribulation and distress, all those who trust in him, so that they shall as surely escape unhurt, as the bush, though enveloped with fire, was unburnt.

The top of the head, etc. - The same words are used by Jacob in blessing this tribe, Gen 49:26. The meaning appears to be that God should distinguish this tribe in a particular way, as Joseph himself was separated, נזיר nazir, a Nazarite, a consecrated prince to God, from among and in preference to all his brethren. See the notes on Gen 49:25, etc.