Is it necessary to stand for someone who approaches, and is one who stands for him sinful?

Standing for an arriving person is not obligatory; rather, it is a matter of noble character. The Prophet, peace and blessings be upon him, stood for Fatimah, and the Companions stood for Sa'd ibn Mu'adh, and Talhah stood for Ka'b ibn Malik.

Standing is of three types: 1. Forbidden (Muharram): To stand over someone who is seated, out of magnification, like the magnification of kings by non-Arabs. 2. Disliked (Makruh): To stand for another person who is standing, upon their entry or exit, merely out of magnification without an embrace or handshake. 3. Permissible, even Recommended (Ja'iz bal Mustahabb): To stand to meet the arriving person, to shake their hand, or to take their hand to guide them to a place. This is from the Sunnah.