I can’t think of anywhere in the Bible that says “angels cannot lie”, but numerous verses make it plain that angels cannot lie. Some of these verses:
Psalm 5:4-6 For you are not a God who delights in wickedness; evil may not dwell with you. The boastful shall not stand before your eyes; you hate all evildoers. You destroy those who speak lies; the LORD abhors the bloodthirsty and deceitful man.
God obviously wouldn’t tolerate lying in his angels.
Psalm 101:7 No one who practices deceit shall dwell in my house; no one who utters lies shall continue before my eyes.
Angels behold the face of God (see verse below). If they uttered lies, they wouldn’t continue before God.
Matthew 18:10 “See that you do not despise one of these little ones. For I tell you that in heaven their angels always see the face of my Father who is in heaven.”
Psalm 5:4-6 For you are not a God who delights in wickedness; evil may not dwell with you. The boastful shall not stand before your eyes; you hate all evildoers. You destroy those who speak lies; the LORD abhors the bloodthirsty and deceitful man.