William Burkitt on Matthew 13:47

The design and scope of this parable also is to set forth the state of the gospel church, which is like a floor, where chaff is mixed with wheat; a field, where tares are mixed with good corn; a net, where bad fishes are involved with the good. As the wheat must not be removed out of the floor before the time of winnowing; nor the tares gathered out of the field before the time of reaping; nor the good fishes break through the net to get from the bad before the time of separation; so must not Christians forsake a church's communion, because of the present mixture of good and bad in the church. For a mixed communion, in the church, and the good Christians communicating with the bad, do neither defile the ordinances of Christ, nor pollute those that sincerely join in them.