Adam Clarke on Matthew 20:11

They murmured - The Jews made the preaching of the Gospel to the Gentiles, a pretense why they should reject that Gospel; as they fondly imagined they were, and should be, the sole objects of the Divine approbation. How they murmured because the Gentiles were made partakers of the kingdom of God; see Act 11:1, etc., and Act 15:1, etc. There are many similitudes of this kind among the Jews, where the principal part even of the phraseology of our Lord's parable may be found. Several of them may be seen in Schoettgen. Our Lord, however, as in all other cases, has greatly improved the language, scope, design, and point of the similitude. He was, in all cases, an eminent master of the sentences.