What is the meaning of "va'Yman"?
Radak: It is summonsing, like "Mnah Es Ma'achalchem" (Daniel 1:10). Hashem summonsed it at the time they cast Yonah, and he did not drown. This was one of the miracles. Pirkei d'R. Eliezer 10 says that it was summonsed from the six days of creation to swallow him.
Obviously, a fish that can swallow a person is big. Why must the verse teach that it was big?
Malbim: It was able to swallow him intact, without breaking his bones.
Here it says that a Dag swallowed him. The coming verse says that he was in a Dagah!
Rashi citing Pirkei d'R. Eliezer 10: A male swallowed him. He had space, and did not put to his heart to pray. Hashem hinted to the fish, and it vomited him into a female's mouth. It was full of fetuses, and Yonason was cramped there, and prayed "mi'Me'ei ha'Dagah" (2).
Radak (2): Dag can be masculine or feminine - "veha'Dagah Asher ba'Y'or Mesah" (Shemos 7:21).
Malbim: 'Dag' includes masculine and feminine. 'Dagah' is a collection of fish, e.g. "veha'Dagah Asher ba'Y'or Mesah." "Mi'Me'ei ha'Dagah" (2) shows that there was a collection of many fish in its womb. There can be many tens of thousands of eggs in a fish.
How could he live inside the fish? A person needs to breathe cold air!
Radak (2): This was a miracle. Another miracle was that he was not confounded; his intellect was settled, and he prayed (2).
Malbim citing Mahari: Since death was decreed on him, it was as if he was born again. Hashem gave to him the nature of a fetus which lives nine months in its mother's womb without breathing. This was a miracle like Chananyah, Misha'el and Azaryah in the furnace!
