In a parliamentary system of government, the minister in charge accepts responsibility, and the cabinet as a whole must also accept responsibility. Yishai should stand down, and an independent enquiry must take place. Clearly no one person alone can be held fully responsible. If he rejected fire engines donated by Christian friends of Israel, this must also be fully investigated. You can't turn down fire engines and then complain you haven't got enough!
Abbas to urge UN to pressure Israel to permit entrance to Palestinian refugees from Syria (Haaretz)