Which made oil within their walls - Or rather, they compel them to express oil within their walls. The word יצהירו yatshı̂yrû, rendered "made oil," is from צחר tsachar, to shine, to give light; and hence, the derivatives of the word are used to denote light, and then oil, and thence the word comes to denote to press out oil for the purpose of light. Oil was obtained for this purpose from olives by pressing them, and the idea here is, that the poor were compelled to engage in this service for others without compensation. The expression "within their walls," means probably within the walls of the rich; that is, within the enclosures where such presses were erected. They were taken away from their homes; compelled to toil for others; and confined for this purpose within enclosures erected for the purpose of expressing oil. Some have proposed to read this passage, "Between their walls they make them toil at noonday;" as if it referred to the cruelty of causing them to labor in the sweltering heat of the sun. But the former interpretation is the most common, and best agrees with the usual meaning of the word, and with the connection.
And tread their wine-presses and suffer thirst - They compel them to tread out their grapes without allowing them to slake their thirst from the wine. Such a treatment would, of course, be cruel oppression. A similar description is given by Addison in his letter from Italy:
Il povreo Abitante mira indarno
Il roseggiante Arancio e'l pingue grano,
Crescer dolente ei mira ed oli, e vini,
E de mirti odorar l' ombra ei sdegna.
In mezzo alla Bonta della Natura
Maledetto languisce, e deatro a cariche
Di vino vigne muore per la sete.
"The poor inhabitant beholds in vain
The reddening orange and the swelling grain;
Joyless he sees the growing oils and wines
And in the myrtle's fragrant shade repines;
Starves, in the midst of nature's bounty curst,
And in the loaden vineyard dies for thirst."
Addison's works, vol. i. pp. 51-53. Ed. Lond. 1721.

Make oil within their walls - Thus stripped of all that on which they depended for clothing and food, they are obliged to become vassals to their lord, labor in the fields on scanty fare, or tread their wine-presses, from the produce of which they are not permitted to quench their thirst.

[Which] make oil (l) within their walls, [and] tread [their] winepresses, and suffer thirst.
(l) In such places which are appointed for that purpose; meaning, that those who labour for the wicked, are pined for hunger.

Which make oil within their walls,.... Not the poor within their own walls; as if the sense was, that they made their oil in a private manner within the walls of their houses, or in their cellars, lest it should be known and taken away from them; for such cannot be thought to have had oliveyards to make oil of; rather within the walls of their rich masters, where they were kept closely confined to their work, as if in a prison; or within the walls and fences of their oliveyards, where their olive presses stood; or best of all "within the rows (q) of their olive trees", as the word signifies, where having gathered the olives, they pressed out the oil in the presses and this they did at noon, in the heat of the day, as the word (r) for making oil is observed by some to signify, and yet had nothing given them to quench their thirst, as follows:
and tread their winepresses, and suffer thirst; after having gathered their grapes from their vines for them, they trod them in the winepresses, and made their wine, and yet would not allow them to drink of it to allay their thirst.
(q) "inter ordines", Mercerus, Piscator, Cocceius; so Sephorno, and some in Eliae Tishbi, p. 241. (r) "meridiati sunt", V. L. so Bolducius, Schultens.

Which--"They," the poor, "press the oil within their wall"; namely, not only in the open fields (Job 24:10), but also in the wall-enclosed vineyards and olive gardens of the oppressor (Isaiah 5:5). Yet they are not allowed to quench their "thirst" with the grapes and olives. Here, thirsty; Job 24:10, hungry.

Walls - Within the walls of the oppressors for their use. Suffer - Because they are not permitted to quench their thirst out of the wine which they make.