This quote comes from Warren Wiersbe in his book The Elements of Preaching:
If the preacher has done his heart-work and his homework, he should be able to state in one sentence exactly what his message is about and what he wants to accomplish.
Can you state in one sentence what your sermon is about and what you hope to see happen in the hearer’s lives? This is a good and practical challenge for any preacher. Have a great day tomorrow!