Matthew 13:36

‘Then he left the crowds, and went into the house, and his disciples came to him, saying, “Explain to us the parable of the tares (darnel) of the field.” '

The session of preaching to the crowds being over Jesus retired into the house (compare Matthew 13:1), and His disciples then came to Him and asked Him the meaning of the parable of the darnel sowed among the wheat. We do not necessarily have to assume that this was immediately after He had finished preaching. They might well have given Him time to rest first. Nor were the disciples necessarily totally baffled. Perhaps they just wanted to make sure that they had got their interpretation right. But the fact that they had to ask does demonstrate that while they had ‘understanding' it was not full understanding.

‘Explain to us the parable.' The difference between them and the crowds was mainly that they wanted to be sure that they had it right, and therefore asked.