1 Corinthians 8:7

8:7 But this knowledge is not shared by all. And some, by being accustomed to idols in former times, eat this food as an idol sacrifice, and their conscience, because it is weak, is defiled.

Hebrews 9:14

9:14 how much more will the blood of Christ, who through the eternal Spirit offered himself without blemish to God, purify our ¹  consciences from dead works to worship the living God.

Hebrews 10:22

10:22 let us draw near with a sincere heart in the assurance that faith brings, ²  because we have had our hearts sprinkled clean from an evil conscience ³  and our bodies washed in pure water.

[9:14]  ¹ tc The reading adopted by the translation is attested by many authorities (A D* K P 365 1739* al). But many others (א D² 0278 33 1739^c 1881 Ï lat sa) read “your” instead of “our.” The diversity of evidence makes this a difficult case to decide from external evidence alone. The first and second person pronouns differ by only one letter in Greek, as in English, also making this problem difficult to decide based on internal evidence and transcriptional probability. In the context, the author’s description of sacrificial activities seems to invite the reader to compare his own possible participation in OT liturgy as over against the completed work of Christ, so the second person pronoun “your” might make more sense. On the other hand, TCGNT 599 argues that “our” is preferable because the author of Hebrews uses direct address (i.e., the second person) only in the hortatory sections. What is more, the author seems to prefer the first person in explanatory remarks or when giving the logical grounds for an assertion (cf. Heb 4:15; 7:14). It is hard to reach a definitive conclusion in this case, but the data lean slightly in favor of the first person pronoun.

[10:22]  ² tn Grk “in assurance of faith.”

[10:22]  ³ sn The phrase our hearts sprinkled clean from an evil conscience combines the OT imagery of the sprinkling with blood to give ritual purity with the emphasis on the interior cleansing provided by the new covenant: It is the heart that is cleansed and the conscience made perfect (cf. Heb 8:10; 9:9, 14; 10:2, 16).