John Chrysostom

But when the stream was dried up by which the cup of the righteous man was filled, God said, Go to Sarepta, a city of Sidon; there I wall command a widow woman to feed you. As it follows, But to none of them was Elias sent, save unto Sarepta, a city of Sidon, unto a woman that was a widow. And this was brought to pass by a particular appointment of God. For God made him go a long journey, as far as Sidon, in order that having seen the famine of the country he should ask for rain from the Lord. …

Catena Aurea by Aquinas ↗

Basil of Caesarea

Every widowed soul, bereft of virtue and divine knowledge, as soon as she receives the divine word, knowing her own failings, learns to nourish it with the bread of virtue, and to water the teaching of virtue from the fountain of life.

Catena Aurea by Aquinas ↗

Bede

Sidonia signifies a vain pursuit, Sarepta fire, or scarcity of bread. By all which things the Gentiles are signified, who, given up to vain pursuits, (following gain and worldly business,) were suffering from the flames of fleshly lusts, and the want of spiritual bread, until Elias, (i. e. the word of prophecy,) now that the interpretation of the Scriptures had ceased because of the faithlessness of the Jews, came to the Church, that being received into the hearts of believers he might feed and refresh them.

Catena Aurea by Aquinas ↗

Bonaventure

And although they were in such great necessity, it is added: And to none of them was Elijah sent, to relieve them by a miracle from the want of famine, so that the word of the Psalm might be verified in them: "Hungering and thirsting, their soul fainted within them." But he relieved a foreign woman, whence he adds: Except to Sarepta of Sidon, to a widow woman, according to what is written in 3 Kings 17: It was said to Elijah: "Arise and go to Sarepta of the Sidonians and remain there: for I have commanded a widow woman there to feed …

Commentary on Luke, Chapter 4 ↗