I found this hymn on another blog (click here) and the owner very kindly said that she was happy for me to post it here.
The hymn is based on 2 Corinthians 12 v 9-10:
"And He said unto me, My grace is sufficient for thee: for My strength is made perfect in weakness. Most gladly therefore will I rather glory in my infirmities, that the power of Christ may rest upon me. Therefore I take pleasure in infirmities, in reproaches, in necessities, in persecutions, in distresses for Christ's sake: for when I am weak, then am I strong."
Let me but hear my Saviour say,
"Strength shall be equal to the day,"
Then I rejoice in deep distress,
Leaning on His sufficient grace.
I glory in infirmity,
That Christ's own power may rest on me;
When I am weak, then am I strong,
Grace is my shield, and Christ my song.
But if the Lord be once withdrawn,
And we attempt the work alone,
When new temptations spring and rise,
We find how great our weakness is.
I can do all things, or can bear
All sufferings, if my Lord be there:
Sweet pleasures mingle with the pains,
While His kind hand my soul sustains.
Isaac Watts, 1674 - 1748