Verses with the word causeless in the Old Testament (2 verses):

1 Samuel 25:31
That this shall be no grief unto thee, nor offence of heart unto my lord, either that thou hast shed blood causeless, or that my lord hath avenged himself: but when the LORD shall have dealt well with my lord, then remember thine handmaid.

Proverbs 26:2
As the bird by wandering, as the swallow by flying, so the curse causeless shall not come.