John Calvin on Matthew 21:30-31

30. I, Sir. “Seigneur, j’y vay;” — “Sir, I go to it.” This phrase is borrowed from the Hebrew language; for, when the Hebrews wish to offer their services, and to declare that they are ready to obey, they speak in this manner, “Here I am, Sir,” It is a laudable virtue in itself, as soon as God has spoken, to yield to Him ready and cheerful obedience; and Christ does not here give the commendation to slowness. But as both are improper—to delay before doing your duty, and to promise what you do not perform—Christ shows that this hypocrisy is less to be endured than the fierceness which, in process of time, is subdued.