Psalms of Solomon 17:36
32 He will be a righteous king over them, taught by God, there will be no unrighteousness among them during his reign, because everyone will be holy, and their king will be the Lord Messiah. 33 For he will not depend on cavalry and archers; Nor will he need to finance a war; He will not place his hope on making war. 34 The Lord himself is his king, the hope of the one who hopes in God. He will be merciful to all the Gentiles that fearfully stand before him. 35 He will strike the earth with the word of his mouth forever; He will bless the Lord's people with wisdom and happiness. 36 And he himself will be free from sin, in order to rule such a great people. He will expose officials and drive out sinners by the strength of his word. 37 And he will not weaken during his reign, relying upon his God, because God will make him powerful by a holy spirit; and wise in intelligent counsel, with strength and righteousness.
Hebrews 4:15
12 For the word of God is living and active and sharper than any double-edged sword, piercing even to the point of dividing soul from spirit, and joints from marrow; it is able to judge the desires and thoughts of the heart. 13 And no creature is hidden from God, but everything is naked and exposed to the eyes of him to whom we must render an account. 14 Therefore since we have a great high priest who has passed through the heavens, Jesus the Son of God, let us hold fast to our confession. 15 For we do not have a high priest incapable of sympathizing with our weaknesses, but one who has been tempted in every way just as we are, yet without sin. 16 Therefore let us confidently approach the throne of grace to receive mercy and find grace whenever we need help.
Notes and References
"... Hebrews follows a common Christian tradition in declaring that Jesus was 'without sin' (4:15), 'holy, blameless, undefiled, separated from sinners' (7:26), who 'offered himself without blemish to God' (9:14). Hebrews' idea of Jesus' sinlessness was not derived in any simple way from current views of priesthood or messianic expectation, although it was compatible with such ideas. The messianic 'Branch' of David was to be righteous (Jeremiah 23:5-6; 3 3:15-16; Isaiah 9:7; 11:1-5), and the Messiah was to 'be clean of sin' (Psalms of Solomon 17:36) and to oppose sin and unrighteousness (17:22-32; compare Hebrews 1:8-9). Priests were expected, not to be sinless, but to minister in a state of purity. Some anticipated an eschatological priest who would make sin to cease (CD XII, 23; Testament of Levi 18:9), and Philo spoke of the Logos as a priest, 'immune from all unrighteousness.' None of these sources, however, portrays sinlessness as obedience in suffering, as does Hebrews ..."
Koester, Craig R. Hebrews: A New Translation with Introduction and Commentary (p. 294) Yale University Press, 2010