John Lightfoot on John 18:1

[Over the brook Cedron.] There is a question among expositors about the article in the plural number, and the accent in Cedron; and that upon this occasion, that it might not be thought as if any relation were to be had here to Cedars, wherein one hath been deceived when he thus comments upon it: "It is called the brook Cedron, that is, of Cedars, that grow there." So also the Arab. Interp. in this place, over the brook of Cedar. But in 2 Samuel 15:23, and 1 Kings 2:37, he retains the word Cedron.

Amongst the Talmudists, kedar signifies dung: where the Gloss renders kedar by the easing of nature. Aruch renders it by dung: and the sense of that clause is, More die of inconvenient easing nature than of hunger. I would not affirm that the word kedar was used in this sense in the primitive denomination of the brook Kidron; but rather that the brook was called so from blackness; the waters being blackened by the mud and dirt that ran into it; it being, indeed, rather the sink or common sewer of the city than a brook.

But when the word kedar was used for dung, which it might be at that time when the Greek version was made, perhaps those interpreters might translate the Hebrew word into Greek, which is not unusual with them; so that the brook Cedron might be the same with them as the brook of filth.

[Where was a garden.] The grandees of the nation had their gardens and places of pleasure about the city, yea, even in the mount of Olives: for there were none within the city itself. "The blood that was over and above, after the sprinkling of the inward altar, was poured out towards the foundation on the west of the outward altar. And the blood that was over and above at the outward altar was poured out at the foot of it on the south side: and both the one and the other meeting together ran down through a conveyance under ground into the brook Kidron; and was sold to the gardeners to dung their gardens with; which having bought they used for that purpose."

For the blood, having been once dedicated to sacred use, might not be put to any common use without trespass; so that the gardeners paid so much money for it as would purchase a trespass offering.