To my understanding, the USSR was very strong in promoting an anti-religion view, so it seems odd to respect a religious tradition like this, even for the dead.
They promoted state atheism, but respect for religious individuals rights still existed to a small extent.
Muslim majority states made up a large part of the Soviet Union, such as Azerbaijan, Kazakhstan, Uzbekistan, Turkmenistan, etc. so the Soviet government respected them to that regard.
However, they did close Mosques and it took the a while to allow for Imams to be educated in cities
Lenin himself, oversaw a sacred religious icon, a Qur'an belonging to Uthman, a companion of the Islamic Prophet Muhammad being given as a gift to the Muslim community.
This was part of Bolshevik policy to try to make amends for the crimes of Tsarism in the former colonies. Bolshevik leaders such as Lenin and Trotsky understood that this was not only basic justice, but it was also necessary to clear the ground and enable class divisions in Muslim society to come to the fore.
Some Islamic laws were institutionalised into law.
And the Muslim holy day, Friday, was made a day of rest in central Asia, where the vast majority of the soviet Muslims were.
Things changed under Stalin and they were oppressed, to the point where Stalin even tried to ban a variant of the Hijab, this however backfired on him.