Targum zu Bamidbar 7:88

And all the oxen for consecrated victims, twenty-four, answering to the twenty-four orders (of the priests); the rams, sixty, answering, to the sixty years which Izhak had lived when he begat Jakob; the goats, sixty, answering to the sixty letters in the benediction of the priests; lambs of the year, sixty, to atone for the sixty myriads of Israel. This was the dedication of the altar by anointment on the day that they anointed it.