Matthew 15:24 - Ellicott's Commentary On The Whole Bible

I am not sent (better, I was not sent) but unto the lost sheep of the house of Israel. — This, then, was what had restrained Him. Those wandering sheep, without a shepherd, were the appointed objects of His care. Were He to go beyond that limit in a single case, it might be followed by a thousand, and then, becoming, as it were, before the time, the Apostle of the Gentiles, He would cease to draw to Himself the hearts of Israel as their Redeemer. We call to mind the case of the centurion’s servant (Matthew 8:10), and wonder that that was not decisive as a precedent in the supplicant’s favour. The two cases stood, however, on a very different footing. The centurion who had built a synagogue was practically, if not formally, a proselyte of the gate. As the elders of the synagogue pleaded for him as worthy, the work of healing wrought for him would not alienate them or their followers. The woman belonged, on the contrary, to the most scorned and hated of all heathen races, to the Canaan on which the primeval curse was held to rest (Genesis 9:25), and had as yet done nothing to show that she was in any sense a convert to the faith of Israel.