Rashi on Deuteronomy
מענה אלהי קדם A DWELLING PLACE FOR THE ANCIENT GOD (This must be connected with the preceding): — The skies serve as a dwelling place for the ancient God, i.e. the God Who pre-existed (קדם) all gods, for He selected the skies as His residence and dwelling place, ומתחת AND BENEATH His dwelling place, all the mighty men (men of strong arm, זרוע) dwell.
Sforno on Deuteronomy
אלוקי קדם, the true G’d ever since the beginning of all existence. Anything that is of more recent origin has been called into existence by this G’d.
Tur HaArokh
מעונה אלוקי קדם, “that (the שחקים at the end of the last verse) is the abode of G’d since days immemorial.” Some commentators understand this phrase as meaning: “Your abode is that of the Immemorial G’d.”