They demonstrate Sinbad's respectability and his generosity toward the porter.
Explanation:
In this passage, Sinbad's respectability and generosity are obvious from the way he is being described by the speaker. He tells us that Sinbad is magnificent, and that his is a noble company. However, the speaker also tells us that Sinbad was generous, as he invited the porter to sit next to him, poured him some wine and asked him his name and occupation. Therefore, these phrases demonstrate Sinbad's respectability and generosity.
