The fast of the fourth month, etc. (For the occasions of these fasts, see note on Zechariah 7:3.) Jerome gives the later Jewish traditions concerning them. The fast of the seventh day of the fourth month commemorated the breaking of the two tables of the commandments by Moses, as well as the first breach in the walls of Jerusalem; that of the fifth month was observed in memory of the return of the spies sent to explore Canaan, and the consequent punishment of forty years' wandering in the wilderness, as well as of the burning of the temple by the Chaldeans; that in the tenth month was appointed because it was then that Ezekiel and the captive Jews received intelligence of the complete destruction of the temple.
Joy and gladness. The observance of these fasts seems, by the Lord's answer, to have been neither enjoined nor forbidden; but as for their sins their festivals had been turned into mourning (Amos 8:10), so now their fasts should be turned into joyful feasts, and former miseries should be forgotten in the presence of the blessings now showered upon them.
Therefore love the truth and peace. This is the condition of the fulfilment of the promise (verse 16; Zechariah 7:9), here again forcibly impressed.