Q: Is it permissible to stand in honor of a national anthem or flag?
A: It is not permissible for a Muslim to stand in honor of a national anthem or flag; this is a repudiated Bid‘ah (innovation in religion) as it did not happen during the time of the Messenger of Allah (peace be upon him) or that of the Rightly-Guided Caliphs (may Allah be pleased with them). It also runs counter to the perfection of due, pure Tawhid (monotheism) and to the sincerity of dedicating all glorifications to Allah Alone. It is a means that can lead to Shirk (associating others with Allah in His Divinity or worship) and involves imitation of the Kufar (disbelievers) and their bad customs, as well as their excessive glorification of their leaders and their exaggerated ceremonies. The Prophet (peace be upon him) prohibited acting like and imitating the disbelievers.
May Allah grant us success. May peace and blessings be upon our Prophet Muhammad, his family, and Companions.
Also Shaykh Abdul-Muhsin al-Abbaad was asked:
In our lands, if the national anthem is played it is obligatory on everyone who hears it to stand for it. Is there forbiddence in this?
“Yes, in it there is harm and it is something forbidden”.
[Sharh Sunan Abi Dawood no. 593]
Faisal Ibn Abdul Qaadir Ibn Hassan