Surah 2. Al-Baqara, Ayah 95

 i.e., disobeying Allah, killing some of the prophets (including Zachariah and John the Baptist), claiming to have killed Jesus, accusing Mary of adultery, and dealing with usury. See 4:153-158.

The phrase "What their hands have sent on before them" frequently occurs in the Qur-an. Here, and in many places, it refers to sins. In such passages as lxxviii. 40, or lxxxi. 14, it is implied that both good and bad deeds go before us to the judgement seat of God before we do ourselves. In ii. 110, it is the good that goes before us. Our deeds are personified. They are witnesses for or against us, and they always go before us. Their good or bad influence begins to operate before we even know it. This is more general than the New Testament idea in the First Epistle of St. Paul to Timothy, v. 24: "Some men's sins are open beforehand, going before to judgment; and some men they follow after."