'Mourning' in the Bible

Remove her prisoner's clothing and let her remain for a month in your house, mourning her parents. After that, you may become her husband and she is to become your wife.

"I've removed the holy offering from my house and given it to the descendants of Levi, to the foreigners, to the orphans, and to the widows just as you have commanded me. I haven't violated or forgotten your commands. I haven't eaten any part of it while mourning, nor removed any part of it while unclean, nor offered any of it to the dead. I've obeyed the voice of the LORD my God and did all that he commanded me.

The Israelis mourned for Moses at the desert plain of Moab for 30 days, after which the period of mourning for Moses was completed.