To strike hands

to make a contract, or to become surety for another's debt or good behavior.

See also: Hand

Webster's Revised Unabridged Dictionary, published 1913 by G. & C. Merriam Co.
References in classic literature ?
Then suddenly, with the same resolution with which he used to strike hands when making a good purchase, he took a step back and turning up his sleeves began raking the snow off Nikita and out of the sledge.
The decision to strike hands ScotRail the moral high ground.