Isaiah 8:3 (BSB)

And I had relations with the prophetess, and she conceived and gave birth to a son. The LORD said to me, “Name him Maher-shalal-hash-baz.

From Isaiah 8. Also in the ESV.

Commentary on Isaiah 8:3

• John Calvin (Reformed), Calvin's Commentaries on Isaiah 8:3: 3. And I approached to the prophetess. What follows happened to the Prophet, I have no doubt, by a vision, for the purpose of sealing the former prediction. The vision given to Isaiah was, that he had a child by his wife, and was enjoined to give him this name.
• Matthew Henry (Presbyterian), Matthew Henry's Complete Commentary on Isaiah 8:1-8: In these verses we have a prophecy of the successes of the king of Assyria against Damascus, Samaria, and Judah, that the two former should be laid waste by him, and the last greatly frightened. Here we have, I. Orders given to the prophet to write this prophecy, and publish it to be seen and read of all men, and to leave it upon record...
• John Gill (Reformed Baptist), Exposition of the Old and New Testaments on Isaiah 8:3: And I went unto the prophetess,.... His wife, so called; not because she prophesied, but because she was the wife of a prophet; and besides, the birth of her son later mentioned, and his name, had in them the nature of a prophecy.
• Jamieson-Fausset-Brown (Reformed), Commentary Critical and Explanatory on the Whole Bible on Isaiah 8:3: prophetess--perhaps the same as the "virgin" (Isa 7:14), in the interim married as Isaiah's second wife: this is in the primary and temporary sense. Immanuel is even in this sense distinct from Maher-shalal-hash-baz. Thus nineteen months at least intervene from the prophecy (Isa 7:14), nine before the birth of Immanuel, and ten from that time to the birth of Maher-shalal-hash-baz: adding eleven or twelve months...