'Duty' in the Bible

“You shall not see your countryman’s ox or his sheep straying away or being stolen, and ignore [your duty to help] them; you shall certainly take them back to him.

You shall do this with his donkey or with his garment or with anything that your countryman has lost and you have found. You are not allowed to ignore [your duty to help] them.

You shall not see your countryman’s donkey or his ox fall down along the road, and ignore [your duty to help] them; you shall certainly help him lift it up.

“When a man takes a bride, he must not go out with the army or be liable for any duty. He is free to stay at home for one year, so that he can bring joy to the wife he has married.

If brethren dwell together, and one of them die, and have no child, the wife of the dead shall not marry without unto a stranger: her husband's brother shall go in unto her, and take her to him to wife, and perform the duty of an husband's brother unto her.

And if the man like not to take his brother's wife, then let his brother's wife go up to the gate unto the elders, and say, My husband's brother refuseth to raise up unto his brother a name in Israel, he will not perform the duty of my husband's brother.