Who can - Greek, “being able”; not pleasing himself (Rom 15:3).
have compassion - Greek, “estimate mildly,” “feel leniently,” or “moderately towards”; “to make allowance for”; not showing stern rigor save to the obstinate (Heb 10:28).
ignorant - sins not committed in resistance of light and knowledge, but as Paul’s past sin (1Ti 1:13). No sacrifice was appointed for willful sin committed with a high hand; for such were to be punished with death; all other sins, namely, ignorances and errors, were confessed and expiated with sacrifices by the high priest.
out of the way - not deliberately and altogether willfully erring, but deluded through the fraud of Satan and their own carnal frailty and thoughtlessness.
infirmity - moral weakness which is sinful, and makes men capable of sin, and so requires to be expiated by sacrifices. This kind of “infirmity” Christ had not; He had the “infirmity” of body whereby He was capable of suffering and death.