Qitzur Shulchan Arukh – 62:14
One who gives money to a friend to buy for him land or goods [as his agent], and the agent went and bought the object with his own money for himself, this one is deceitful. If he bought it with the money he was given, he is obliged to give him it, even if he [was trying to] buy it for himself.
A continuation of the theme we began yesterday. Committing to a deal is not fiscally binding until the deal is complete, but there is a lack of yosheir (integrity) in breaking one’s word.