How sound is what I read about the Prophet’s — may Allah bless him and grant him peace — command to bury seven things from a human, and how is it possible to collect hair and bury blood in cities?

There are weak narrations regarding the command to bury hair, nails, blood, teeth, the foreskin, and the placenta, but their content aligns with the sanctity and dignity of the human being. If burial is not feasible, one can dispose of them by placing them in drains or sewers, so they are out of sight; for the Prophet, peace and blessings be upon him, commanded Abdullah ibn Al-Zubayr to spill his blood in a place where no one would see it. As for fallen hair that is difficult to collect, there is no harm in leaving it.