His crime, allegedly confessed under torture: agreeing to sell a piece of land to (gasp) a Jew.
His sentencers: the Palestinian Authority.
Side note: Palestinian law does not prohibit Palestinians from selling to Israeli citizens. Israeli citizens of Arab extraction can and do buy land in the West Bank. However, the act of selling to JEWS is specifically prohibited and is generally punished by execution or by hard labor for at least five years.
In Israel itself, Israeli Jews and Israeli Arabs can sell to each other, or to Druze, atheists, Baha’i, or whomever. Israeli law makes no distinction between citizens’ property rights.