John Dummelow's Commentary on the Bible - Matthew 5:1-48
The Sermon on the MountJohn 5:1 to John 7:29. The Sermon on the Mount: see Luke 6:20. This sermon is so similar to the sermon reported by St. Luke (Luke 6:20), that it is best to regard them as identically the same. It is true that it has been plausibly suggested that our Lord during His preaching tours often repeated nearly the same sermon to different audiences, and that St. Matthew has given us the sermon as delivered at one place and St. Luke as delivered at another, but the resemblances... read more
Expository Notes of Dr. Thomas Constable - Matthew 5:34-36
Jesus cut through all the casuistry by saying that if oaths that God intended to guarantee truthfulness in speech become the instruments of deceit, it is better to avoid oaths altogether. Again Jesus got below the external act to the real issue at stake that had been God’s concern from the beginning. The way to dispense with false swearing is to avoid all swearing. Righteous people should not need to confirm their statements with an appeal to a higher authority. Their word should be enough (cf.... read more