ISB ~ Mark 12 v19

if a man’s brother dies:The Sadducees draw attention to the levirate law of Deut 25:5-6.

• This law required a man to marry his brother’s widow if the brother died childless (Gen 38:6-8). The man would thus produce children for his deceased brother and carry on his family name in Israel. The Sadducees considered this legislation inconsistent with a belief in bodily resurrection, since the widow’s numerous marriages would only lead to confusion if all of her husbands were raised.