When his ruler sent him a gift of pre-cooked food, he straightened his mat and was the first person to taste it. When his ruler sent him a present of raw meat, he cooked it and offered it to the spirits of his ancestors. When his ruler gave him a live animal, he reared it. When dining with his ruler, he was the first one to taste the food after the ruler had performed the sacrificial offering.
We are back to the rituals that a gentleman should follow, this time when he receives gifts of food from his ruler and when he goes to visit his ruler for dinner.
Note that the gentleman needs to show he has total trust in his ruler by eating the pre-cooked food first rather than having one of his servants or retainers try it out beforehand to make sure it isn’t spoiled or perhaps even poisoned.
The ruler could of course just be showing great courtesy by having his gentleman guest eat first, but such a ritual would at the same time serve as a useful self-preservation mechanism.