This phrase explains who the Sadducees were. This can be written more clearly. AT: "who say there is no resurrection from the dead" (See: [[rc://en/ta/man/translate/figs-explicit]])
# Moses wrote for us, 'If a man's brother dies
The Sadducees are quoting what Moses had written in the law. Moses' quote can be expressed as an indirect quote. AT: "Moses wrote for us that if a man's brother dies" (See: [[rc://en/ta/man/translate/figs-quotations]])
# wrote for us
"wrote for us Jews." The Sadducees were a group of Jews. Here they use the word "us" to refer to themselves and all Jews.
This means the children will be considered the dead brother's descendants. This can be made explicit. AT: "have children for his brother who will be considered his descendants" (See: [[rc://en/ta/man/translate/figs-explicit]])