{9} But though he had done so many miracles before them, yet they believed not on him:

(9) Faith is not of nature, but of grace.

People's New Testament

12:37 Yet they believed not on him. They had a kind of intellectual faith, but were filled with doubts when they could not understand. There was no real trust.

Wesley's Notes

12:37 Though he had done so many miracles before them - So that they could not but see them.

Jamieson-Fausset-Brown Bible Commentary

37-41. It is the manner of this Evangelist alone to record his own reflections on the scenes he describes; but here, having arrived at what was virtually the close of our Lord's public ministry, he casts an affecting glance over the fruitlessness of His whole ministry on the bulk of the now doomed people.

though he had done so many miracles-The word used suggests their nature as well as number.

Matthew Henry's Concise Commentary

12:37-43 Observe the method of conversion implied here. Sinners are brought to see the reality of Divine things, and to have some knowledge of them. To be converted, and truly turned from sin to Christ, as their Happiness and Portion. God will heal them, will justify and sanctify them; will pardon their sins, which are as bleeding wounds, and mortify their corruptions, which are as lurking diseases. See the power of the world in smothering convictions, from regard to the applause or censure of men. Love of the praise of men, as a by-end in that which is good, will make a man a hypocrite when religion is in fashion, and credit is to be got by it; and love of the praise of men, as a base principle in that which is evil, will make a man an apostate, when religion is in disgrace, and credit is to be lost for it.