I will wash mine hands in innocency: so will I compass thine altar, O LORD:
Wash ... hands - in allusion to Deuteronomy 21:6, where is described the custom of washing the hands over a slain heifer, with a protestation of innocence in the case of an uncertain murder. So Pilate used this symbolical action to clear himself of guilt of murder in the case of Christ (Matthew 27:24). The "hands" are specified as being the instruments of action (cf. Psalms 73:13; Job 9:30). When Aaron and the priests went, into the tabernacle to minister, they washed their hands and their feet. So the Jews, in later times, washed their hands before praying (cf. Isaiah 1:15-16; 1 Timothy 2:8).
Compass thine altar - alluding to the procession of the choristers, singing as they moved round the altar: so in Psalms 26:7 there follows, "that I may publish with the voice of thanksgiving." Compare Septuagint, Psalms 27:6, 'I went round and sacrificed' [ekukloosa kai ethusa]. Thus David's associating with the sacred procession circling round the altar is a beautiful contrast to those sitting in the same circle "with vain persons" (Psalms 26:4). Hengstenberg explains "encompass" in the sense of being strongly attached to. So Cocceius, 'I am constantly about thy altar; I never leave it' in heart' if not in person. Our altar is Christ (Hebrews 13:10). The former is the more common meaning х caabab (H5437)]. It is not so much the outward worship as the inward trust and gratitude (Psalms 26:7) which he resolves ever to continue, and to express before the Church in God's appointed way, through the blood of atonement.