Albert Barnes Commentary Job 31:27

"And my heart hath been secretly enticed, And my mouth hath kissed my hand:" — Job 31:27 (ASV)

And my heart has been secretly enticed—that is, away from God, or led into sin.

Or my mouth has kissed my hand—Margin, "my hand hath kissed my mouth." The margin accords with the Hebrew. It was customary in ancient worship to kiss the idol that was worshipped; compare 1 Kings 19:18, “I have left me seven thousand in Israel - and every mouth which hath not kissed him.” See also Hosea 13:2. The Muslims at the present day, in their worship at Mecca, kiss the black stone which is fastened in the corner of the Beit Allah as often as they pass it when going around the Kaaba. If they cannot come near enough to kiss it, they touch it with the hand and kiss that.

According to Paxton, in some Eastern cultures, a person pays respects to someone of a superior station by kissing their hand and putting it to their forehead. The custom of kissing the hand of a prince, as it exists in Arabia, is also described by Niebuhr (Reisebeschreibung, Vol. 1, p. 414).

This custom also prevailed among the Romans and Greeks. For instance, Pliny says, Inter adorandum dexteram ad osculum referimus, et totum corpus circumagimus. So Lucian, in his work περὶ ὀρχήσεως peri orchēseōs, says, “And the Indians, rising early, adore the sun - not as we, kissing the hand - τὴν χεῖρα κύσαντες tēn cheira kysantes - think that our vow is perfect.”

The foundation of the custom alluded to here is the respect and affection shown for someone by kissing. Since the heavenly bodies that were worshipped were so remote that worshippers could not physically reach them, they expressed their veneration by kissing their hand.

Job means to say that he had never performed an act of homage to the heavenly bodies.