When the ark of the LORD had been in the land of the Philistines seven months,
The first words of the chapter tell us how long the captivity of the ark continued - it was in the country of the Philistines seven months. In the field of the Philistines (so it is in the original), from which some gather that, having tried it in all their cities, and found it a plague to the inhabitants of each, at length they sent...
Commenting on 1 Samuel 6:1-9
And the ark of the Lord was in the country of the Philistines seven months. Or "in the field" (c) of the Philistines; hence Procopius Gazaeus observes, that none of the cities daring to receive the ark, they left it without under the open air, so thinking they should be delivered from their calamity.
And the ark of the LORD was in the country of the Philistines seven months. (a) They thought by continuance of time the plague would have ceased, and so would have kept the ark still.