Rights of the Guests

A host is obliged to honor his guest in Islam. The Prophet said:

Whoever believes in Allah and the Last Day, he shall honor his neighbor. And whoever believes in Allah and the Last Day, he shall honor his guest according to his right.
The man asked: "And what is his right O Messenger of Allah?
He said: "One day and one night and hospitality for three days and whatever is more than that, then it is charity on the host's part. And whoever believes in Allah and the Last Day, he shall speak good or stay quiet.
Bukhari, Hadith no. 5673.

The manners of honoring the guests include warm welcome with a happy face. Similarly it is obligatory on the guest to be considerate about the host's condition and not to overburden him as the Prophet said:

It is not allowed for a Muslim to stay with his brother until he causes him to sin.
They said: O Messenger of Allah! And how does he cause him to sin? He said:
"He stays with him and he does not have anything to offer.