2 Corinthians 12:9

My grace is all you need, for my power is the greatest when you are weak." 

Commentary:

2 Cor. 12:9 My grace is sufficient for you.The present tense of the verb translated “is sufficient” reveals the constant availability of divine grace. God would not remove the thorn, as Paul had requested, but would continually supply him with grace to endure it (cf. 1 Cor. 15:10; Phil. 4:13; Col. 1:29). power is made perfect in weakness. Cf. 2 Cor. 4:7–11.