Scripture where Jesus made an open show of Satan's defeat?

Answer 1

Satan was permanently defeated at the Cross by Jesus, the crucifixion opened the door for all who believe to be forgiven of their sins and go to heaven.

Satan's worst day is yet to come where he himself will be thrown into the lake of his own fire (Revelations 20:10)

But if you are referring to Jesus being tempted by Satan in the desert for 40 days scripture says:

Luke 4:1-14 (New International Version)Luke 4

The Temptation of Jesus1Jesus, full of the Holy Spirit, returned from the Jordan and was led by the Spirit in the desert, 2where for forty days he was tempted by the devil. He ate nothing during those days, and at the end of them he was hungry.

3The devil said to him, "If you are the Son of God, tell this stone to become bread."

4Jesus answered, "It is written: 'Man does not live on bread alone.'[a]"

5The devil led him up to a high place and showed him in an instant all the kingdoms of the world. 6And he said to him, "I will give you all their authority and splendor, for it has been given to me, and I can give it to anyone I want to. 7So if you worship me, it will all be yours."

8Jesus answered, "It is written: 'Worship the Lord your God and serve him only.'[b]"

9The devil led him to Jerusalem and had him stand on the highest point of the temple. "If you are the Son of God," he said, "throw yourself down from here. 10For it is written:

" 'He will command his angels concerning you

to guard you carefully;

11they will lift you up in their hands,

so that you will not strike your foot against a stone.'[c]"

12Jesus answered, "It says: 'Do not put the Lord your God to the test.'[d]"

13When the devil had finished all this tempting, he left him until an opportune time.

Answer 2

Colossians 2:15 (NIV)

And having disarmed the powers and authorities, he made a public spectacle of them, triumphing over them by the cross.