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Ruth 1:5ESV·author unknown

and both Mahlon and Chilion died, so that the woman was left without her two sons and her husband.

Matthew Henry Presbyterian @wholebiblehenry

The first words give all the date we have of this story. It was in the days when the judges ruled (Rut 1:1), not in those disorderly times when there was no king in Israel; but under which of the judges these things happened we are not told, and the conjectures of the learned are very uncertain.

Commenting on Ruth 1:1-5

John Gill Reformed Baptist @doctorgill

And Mahlon and Chilion died also both of them,.... As well as their father, in the land of Moab, after they had lived with their wives in it about ten years; the Targum is,"because they transgressed the decree of the Word of the Lord, and joined in affinity with strange people, their days were cut off;''or shortened: and the woman was left of her two...

Adam Clarke Methodist @methodicalclarke

And Mahlon and Chilion died - The Targum adds, And because they transgressed the decree of the word of the Lord, and joined affinity with strange people, therefore their days were cut off. It is very likely that there is more here than conjecture.