Sayyiduna Ibn Umar (may Allah be pleased with them) narrates from the Messenger of Allah (peace and blessings be upon him) that he said: "The greatest act of kindness is to show kindness to the friends of one's father."
Benefits and Issues: ➊ This means that there are several levels of good conduct, and one of these is to show good conduct towards the friends and acquaintances of one’s parents after their death or in their absence. This is considered the most virtuous form of good conduct because, with a living person, one is mindful of their sense of shame and modesty, whereas, in most cases, such consideration is not shown for the deceased. If someone continues to care for the associates of a person even after their death, then this is truly the greatest form of good conduct.
➋ The way to show good conduct towards parents after their death is to continue the good deeds they used to perform and to support those whom they used to support.
Source: Fadlullah al-Ahad: Urdu Commentary on al-Adab al-Mufrad, Page: 41