Diodati:

V.9 His promise] viz. By which he promised to come, to accomplish the deliverance of those who are is, and the punishment of the wicked. As some men] viz. The scoffers and contemners of God, which have been spoken of, ver. 3. Long-suffering] that is to say, if there be any manner of stay in his coming, as the flesh false conceives, that is not through forgetfulness or slowness, but through patience and to give his Elect time to be converted, and so to make up the number. Not willing] he does not speak of God’s secret and everlasting decree, by which he chooses whom he thinks good, but of the preaching of the Gospel by which all men are invited. The number therefore of the Elect must be made full, before judgement comes. That any] namely of us, or of the Elect, who are is, as we are.

John Diodati, Pious and Learned Annotations upon the Holy Bible: Plainly Expounding the most difficult places thereof, 2^nd edition (London: Printed by Miles Flesher, for Nicolas Fussels, 1648), 2 Peter 3:9, p., 426.