Is inviting friends—including those who helped in obtaining the job—to a luncheon at the farm considered a bribe?

If the aforementioned banquet is not intended to acquire something to which you are not entitled, or to nullify a right, or to establish falsehood, then it is not considered a bribe. Rather, it is something desirable in Islamic law if its intention is to feed people, honor them, and show kindness to those who have shown kindness. This is supported by the Prophet’s (peace be upon him) saying: "O people, spread peace, feed the hungry, maintain kinship ties, and pray at night while people are asleep, and you will enter Paradise in peace." And his saying: "Whoever does you a favor, repay him." And his saying: "Exchange gifts, and you will love each other."