According to the Sunday Times of London, Israeli intelligence tipped off Mahmoud Abbas of an attempt by Hamas to kill him along with Mohammed Dahlan. Though it’s not clear who gave the order, the Times writes:
Hamas’s military wing, the Izza Din Al-Qassem, had planned to kill Abbas at his office in Gaza, intelligence sources said.
Abbas, who became president of the Palestinian Authority last year after the death of Yasser Arafat, was formally warned of the danger by the Israelis and cancelled a planned visit to the territory.