Commentaries:
John had come to grips with this concept. He understood that his role in the vast scope of God's purpose was limited by the overruling wisdom of the Creator as He carried out His purpose. This is a reason why salvation is spoken of as "free"—because God is not bound to show mercy to anybody since all have sinned and come short of the glory of God (Romans 3:23). All too often, we forget that the invisible God is working things out according to His purpose, not ours. God is free to do as He pleases. He owes no one anything.
I Corinthians 4:6-7 adds:
Now these things, brethren, I have figuratively transferred to myself and Apollos for your sakes, that you may learn in us not to think beyond what is written, that none of you may be puffed up on behalf of one against the other. For who makes you differ from another? And what do you have that you did not receive? Now if you did indeed receive it, why do you boast as if you had not received it?
Do we have grounds for being puffed up or jealous? John the Baptist did not think so, and what he declared is truth. I Corinthians 12 makes clear that God places people in the church as it pleases Him, and He gives gifts to them so they can be responsible for a function. The gifts do not make them "better," just prepared by the Creator to serve in a specialized way.
John W. Ritenbaugh
Eating: How Good It Is! (Part Two)
For a person to be humble, he has to understand and fully accept the realization that came from John's innermost being. If he does not, pride will arise and muzzle humility by means of a character weakness. Here, John's disciples feel a measure of jealousy because more people were being attracted to Jesus, and the number of John's disciples was dwindling. John's reply to them is one of wisdom. He understands that God assigns a place in the outworking of His purpose to everyone He calls. John knows and accepts that he had no right to lay claim to an honor that had not been given to him from heaven. Instead of envying Jesus' success, John rejoices that both men's purposes were being fulfilled.
John W. Ritenbaugh
Living by Faith and Humility
Other Forerunner Commentary entries containing John 3:30:
Luke 1:15-17
John 1:6-9
Romans 13:7