Sowing that seed wasn't by your volition as you'd think or want to believe, it was God's idea, he was the one who stared up or troubled your spirit to fulfil a divine or spiritual obligation and the very moment you did, sowing that tithe the assignment was accomplished as you didn't fail or let God down.
Mind you, beyond the above, there a great benefits for you and atonement has been made on your behalf because the heaven and the Lord were pleased and have since kept a record of your action or faith hence, these are 3 letters ' Q.E.D. To sum up the accomplishment of your action.
And please, Note that the man you saw is not in any way the man of God, it was the spirit of God of which you sowed that seed of faith and obedience hence the acknowledgement of your act of faith and obedience to God himself.
Yes, you've seen God but you didn't know it was the Lord himself.
Bless
You.
Jesus is Lord.