William Burkitt on Matthew 15:23

Strange! That a miserable supplicant should cry and sue, whilst the God of mercy is speechless. What! is the fountain of mercy dried up? O Saviour! we have oft found cause to wonder at thy words, but never till now at thy silence.

Learn hence, that Christ doth sometimes delay to return an answer to a well qualified prayer. Sometimes his people do not pray earnestly enough; sometimes they pray too earnestly, for some outward and temporal mercy; sometimes the mercy they pray for is not good for them, or it may be it is not yet good for them. Let us not then judge of God's hearing prayer by his present answer.