Jabir said he intended to go to Khaibar, so he went to the Prophet, gave him a salutation and told him of his purpose. He replied, “When you come to my agent take fifteen camel-loads from him, and if he desires a sign from you put your hand on his collar-bone*”.
*This was evidently a pre-arranged sign to show that the Messenger was genuine.
Hakim b. Hizam said God's Messenger sent him with a dinar to buy a sacrificial animal for him. He bought a sheep for a dinar, sold it for two, came back, bought a sacrificial animal for a dinar, and brought it along with the extra dinar which he had gained. God’s Messenger gave the dinar as sadaqa and asked a blessing on him in his trading.