Hebrews 10:22

(Heb 4:16; Heb 7:19.) with a true heart--without hypocrisy; "in truth, and with a perfect heart"; a heart thoroughly imbued with "the truth" (Heb 10:26). full assurance-- (Heb 6:11); with no doubt as to our acceptance when coming to God by the blood of Christ. As "faith" occurs here, so "hope," and "love," Heb 10:23-24. sprinkled from--that is, sprinkled so as to be cleansed from. evil conscience--a consciousness of guilt unatoned for, and uncleansed away (Heb 10:2; Heb 9:9). Both the hearts and the bodies are cleansed. The legal purifications were with blood of animal victims and with water, and could only cleanse the flesh (Heb 9:13, Heb 9:21). Christ's blood purifies the heart and conscience. The Aaronic priest, in entering the holy place, washed with water (Heb 9:19) in the brazen laver. Believers, as priests to God, are once for all washed in BODY (as distinguished from "hearts") at baptism. As we have an immaterial, and a material nature, the cleansing of both is expressed by "hearts" and "body," the inner and the outer man; so the whole man, material and immaterial. The baptism of the body, however, is not the mere putting away of material filth, nor an act operating by intrinsic efficacy, but the sacramental seal, applied to the outer man, of a spiritual washing (Pe1 3:21). "Body" (not merely "flesh," the carnal part, as Co2 7:1) includes the whole material man, which needs cleansing, as being redeemed, as well as the soul.

— Jamieson-Fausset-Brown Commentary (public domain)