What is the ruling on mentioning one's lineage or association with countries when introducing oneself, and is it part of the Sunnah or blameworthy boasting?

A person mentioning himself or his country for the purpose of introduction is permissible and does not violate the Sunnah. The wisdom behind making people into tribes and nations is for mutual acquaintance, as stated in Ibn Kathir's Tafsir: "{O mankind, indeed We have created you from male and female and made you into peoples and tribes that you may know one another}." Mujahid says regarding "{that you may know one another}": meaning, as it is said, "So-and-so, son of So-and-so, is from such-and-such." Al-Shawkani stated in "Fath al-Qadir" that the benefit is for everyone to attribute themselves to their lineage and not to claim another's. The intent is that Allah created them for this purpose, not for boasting. Mulla Ali al-Qari mentioned in "Sharh Nukhbat al-Fikar" that the Arabs used to attribute themselves to their tribes, and after Islam, they began to attribute themselves to countries due to the loss of many of their lineages. They might also attribute themselves to two countries, as in "al-Misri al-Dimashqi" (the Egyptian-Damascene).