Matthew Poole and continuators on Isaiah 26:7

7 The way of the just is uprightness : thou most upright, dost weigh the path of the just .

Or, most even or plain. Heb. evenness or plainness. Which is understood either, 1. of the Rectitude or Goodness of his Actions or Course: or rather, 2. of the good Success of his Affairs: for this suits best with the Coherence. When the way of the Wicked is rugged, in which they easily stumble and fall into mischief, of which he spoke v. 5, 6. the path of Just men is plain and smooth, and they walk safely and comfortably in it.

The sence of the Words thus rendred is, Thou, O God, who art most upright in all thy ways, and therefore a Lover of Uprightness, and of all upright Men, dost weigh (i. e. examine) the path of the just, the Course of his Actions, and, which is implied, dost approve of them, and therefore direct them to an happy issue. But the Words are otherwise rendred by some late Learned Interpreters, to this purpose, Thou dost level or make plain (as this very Word signifies Psal 78. 50.) the path of the just exactly. Heb. with evenness, or evenly, so as to make it very even. Thus the first Clause declares that it was even or plain, and this sheweth whence or by whom it is made such, even by God.