"When we see sinners in trouble, it is a hopeful sign, and we should pray for them with double importunity (Isaiah 26:2). When we hear them inquiring, we should inquire of the Lord for them. Their prayer should call up ours." - Page 78, Spurgeon's Sermon Notes
Further recommended reading & listening:
The Best of The Daily Spurgeon
The Forgotten Spurgeon, by Iain Murray