John Gill Commentary Deuteronomy 4:19

"and lest thou lift up thine eyes unto heaven, and when thou seest the sun and the moon and the stars, even all the host of heaven, thou be drawn away and worship them, and serve them, which Jehovah thy God hath allotted unto all the peoples under the whole heaven." — Deuteronomy 4:19 (ASV)

And lest you lift up your eyes unto heaven
The starry heaven, which to do in itself is not sinful; and may be lawfully and commendably done, to raise admiration at the wonderful works of God in them, and lead to adore the author of them: but if not guarded against may be ensnaring:

and when you see the sun and the moon, and the stars, [even] all the
host of heaven ;
those bright luminaries, so glorious to behold, and so useful and beneficial to the earth, and the inhabitants of it:

should be driven to worship them, and serve them ;
should have an impulse on their minds and their hearts, be inclined and drawn to the worship of them, partly by considering their splendour, glory, and usefulness, and partly by the example of others; for the worshipping of these seems to be and is the first kind of idolatry men gave into, at least it was very ancient; see (Job 31:26Job 31:27) ,

which the Lord your God has divided unto all nations under the whole
heaven ;
the sun and the moon by their constant revolutions visit all the parts of the world, and stars are fixed in both hemispheres, so that all nations of the earth receive the benefit and advantage of all these heavenly bodies; but were never designed to be the objects of their worship, as might be learnt from their being divided to them, sometimes one part of the earth enjoying them, and then another, and not present with them all at one and the same time, which, if deities, would have been necessary; see (Psalms 19:6) (Matthew 5:45) .