What scripture in the Old Testament does Christ talk about not knowing your left hand from your right hand?
You may be thinking about the passage Matthew 6:1-4, which says, “Take heed that ye do not your alms before men, to be seen of them: otherwise ye have no reward of your Father which is in heaven. Therefore when thou doest thine alms, do not sound a trumpet before thee, as the hypocrites do in the synagogues and in the streets, that they may have glory of men. Verily I say unto you, They have their reward. BUT WHEN THOU DOEST ALMS, LET NOT THY LEFT HAND KNOW WHAT THY RIGHT HAND DOETH: That thine alms may be in secret: and thy Father which seeth in secret himself shall reward thee openly.”
A passage in the Old Testament that does talk about the right and left hand is Deuteronomy 5:32,33, “Ye shall observe to do therefore as the LORD your God hath commanded you: YE SHALL NOT TURN ASIDE TO THE RIGHT HAND OR TO THE LEFT. Ye shall walk in all the ways which the LORD your God hath commanded you, that ye may live, and that it may be well with you, and that ye may prolong your days in the land which ye shall possess.”