2 Tim 1:11-12, Mk 8:38, Lk 9:26, Rom 1:16, Rom 8:17, 2 Tim 2:3,9, 2 Tim 4:5

Whosoever shall be ashamed of Jesus and His words shall be ashamed, when the Son of man comes. (Mk 8:38, Lk 9:26)

Mk 8:38 Whosoever therefore shall be ashamed of me and of my words in this adulterous and sinful generation; of him also shall the Son of man be ashamed, when he cometh in the glory of his Father with the holy angels.

Lk 9:26 For whosoever shall be ashamed of me and of my words, of him shall the Son of man be ashamed, when he shall come in his own glory, and in his Father's, and of the holy angels.

Because Paul preached the gospel that Jesus is the Christ, he suffered suffering and was imprisoned. In those days, when the saints told people that Jesus was the Christ, they were persecuted. Such persecution is shameful in the eyes of others. But Paul was not ashamed of this. Also, Paul asked Timothy to continue preaching the gospel without being ashamed even if he was persecuted while preaching the gospel. (2 Tim 1:8,11-12, Rom 1:16, Rom 8:17, 2 Tim 2:3,9, 2 Tim 4:5)

2 Tim 1:8 Be not thou therefore ashamed of the testimony of our Lord, nor of me his prisoner: but be thou partaker of the afflictions of the gospel according to the power of God; 11 Whereunto I am appointed a preacher, and an apostle, and a teacher of the Gentiles. 12 For the which cause I also suffer these things: nevertheless I am not ashamed: for I know whom I have believed, and am persuaded that he is able to keep that which I have committed unto him against that day.

Rom 1:16 For I am not ashamed of the gospel of Christ: for it is the power of God unto salvation to every one that believeth; to the Jew first, and also to the Greek.

Rom 8:17 And if children, then heirs; heirs of God, and joint-heirs with Christ; if so be that we suffer with him, that we may be also glorified together.

2 Tim 2:3 Thou therefore endure hardness, as a good soldier of Jesus Christ. 9 Wherein I suffer trouble, as an evil doer, even unto bonds; but the word of God is not bound.

2 Tim 4:5 But watch thou in all things, endure afflictions, do the work of an evangelist, make full proof of thy ministry.