What some people do, of standing in silence for a moment, as a salute to the martyrs or prominent figures, or to honour and show respect to their souls, and in mourning for them, is a reprehensible act and an innovation, that was not done at the time of the Prophet (blessings and peace of Allah be upon him) or at the time of his Companions or the righteous earlier generations.
It is not in accordance with the etiquette of Tawheed or sincere veneration towards Allah. Rather it is done by some Muslims who are ignorant of their religion, following the invention of this practice by the disbelievers, and imitating them in their reprehensible customs and their exaggeration about their leaders and prominent figures, both living and dead. The Prophet (blessings and peace of Allah be upon him) forbade us to imitate them.
What is customary in Islam is that the duty of the Muslim is to pray for their dead, to give charity on their behalf, to mention their good qualities and refrain from speaking of their bad qualities… And there is a great deal of etiquette that has been explained by Islam and that the Muslim is encouraged to pay attention to with regard to his brothers, both living and dead. However, that does not include standing for a moment’s silence in honour of the martyrs or prominent figures; Rather this is something that is contrary to the principles of Islam.
And Allah is the source of strength. Blessings and peace of Allah be upon our Prophet Muhammad (pbuh) and his family and companions.
May Allah save us from innovations and may we understand the true spirit of Islam and lead a life of devotion in the light of the guidance provided by the beloved Prophet Muhammad (peace and blessings of Allah be upon him) Ameen.
(Source - Islam Q&A)