Charles Ellicott Commentary Judges 15:4

"And Samson went and caught three hundred foxes, and took firebrands, and turned tail to tail, and put a firebrand in the midst between every two tails." — Judges 15:4 (ASV)

Caught three hundred foxes.—Rather, three hundred jackals. The word Shualim is used for both; but it would be difficult to catch three hundred foxes, whereas jackals are still heard howling in herds around these very regions at night. They must have been even more common in Palestine in ancient times, and therefore we find such names as “the land of Shual” (1 Samuel 13:17), Hazar-shual (“jackal’s enclosure,”Joshua 15:28), Shalim (1 Samuel 11:4), and Shaalabbin (“place of foxes or jackals,”Joshua 19:42). There would have been no difficulty in trapping them, nor is it said that they were all let loose at once.

Turned tail to tail.—This implies that he tied the tails together (Septuagint, sunedēsen; V Vulg., junxit).

Put a firebrand in the midst.—The firebrands were pieces of resinous wood, like Gideon’s torches (Judges 7:20), which were loosely trailed between the tails of the jackals. The object of tying two together was to impede their motion a little, so that they might not dart away so violently as to extinguish the torch.