John Gill Commentary 1 Kings 13:18

"And he said unto him, I also am a prophet as thou art; and an angel spake unto me by the word of Jehovah, saying, Bring him back with thee into thy house, that he may eat bread and drink water. [But] he lied unto him." — 1 Kings 13:18 (ASV)

And he said to him. That is, the old prophet said to the man of God.

I am a prophet also as you are; meaning, that he was a prophet of the true God, and not of any idol deity; that he not only believed in him, and was a worshipper of him, but had revelations from him, and of the same things this man of God had, and that he believed that what he had prophesied of would certainly come to pass.

and an angel spoke to me by the word of the Lord; was sent and dispatched by the order of the Lord with the following message.

saying, bring him back with you into your house, that he may eat
bread and drink water; and so be refreshed, and be fit to proceed on in his journey.

[but] he lied to him; no messenger nor message being sent to him by the Lord, but was wholly a device and stratagem of his own to persuade the man of God to return with him, that he might have his company and conversation.