“Put your trust in God, but keep your powder dry.”
Popularized by Blacker in the poem "Oliver's Advice", http://books.google.com/books?id=JmEaAQAAIAAJ&dq=%22Oliver%27s+Advice%22+Cromwell&q=%22Oliver%27s+Advice%22+Cromwell#v=snippet&q=%22Oliver's%20Advice%22%20Cromwell&f=false published under the pseudonym Fitz Stewart in The Dublin University Magazine, December 1834, p. 700; where the quote is attributed to Oliver Cromwell (hence the poem's title). The repeated line in the poem is "Put your trust in God, my boys, but keep your powder dry."
Misattributed