Where to begin with greetings and hospitality

Question:
A man entered the gathering, and there was an elderly man present. Should he begin the greeting with the right side, or should he greet the elderly man directly if he is in the middle of the gathering?

Answer:
He should greet everyone, starting with the head of the gathering, the eldest in the gathering. The Companions used to begin with the Prophet (peace and blessings be upon him)—the head of the gathering—then with those on his right, and then on his left. If there is awkwardness, or if it might be criticized, or if it leads to a bad impression, he should greet everyone and continue until he reaches the end of the gathering. If he enters a gathering and feels that it is proper etiquette to greet the elder first and then those around him, he should do so. He should do what is most beneficial.
Q: What about tea and coffee?
A: Likewise, he starts with the head of the gathering, then with those on his right, just as they used to start with the Prophet (peace and blessings be upon him), and then pass it to those on his right (peace and blessings be upon him), unless the person on the right allows it to be passed to the left, in which case there is no harm.