Philippians 1:15 (NKJV)

>15 Some indeed preach Christ even from envy and strife, and some also from goodwill:  16 The  former b preach Christ from selfish ambition, not sincerely, supposing to add affliction to my  chains; 17 but the latter out of love, knowing that I am appointed for the defense of the gospel.   

In the book of Philippians  Paul says some preached Christ out of envy so as to add moee afflictions to him.

Was just wondering how the preaching of Christ would add afflictions to his chains

How can one understand the above text?