Sorry. The parable of the two sons that also likens the Pharisees to sons does not begin in verse 20; it begins in verse 28, ( of Matthew 21). And they were Sadducees and elders, but the saducees were no more saved than the pharisees
Yes they both make the word of God without effect by the oral traditions of men called a law of the father. Putting aside there differences to attack the Christians one source of faith as in all things written in the law and the prophets (sola scriptural) The one reforming authority in any generation .That exposes the signs and wonder gospel of those refusing to walk by faith. (the unseen)
Matthew 16:1 The Pharisees also with the Sadducees came, and tempting desired him that he would shew them a sign from heaven.