Passage
Thou hast set a bound which they shall not pass over; neither shall they return to cover the earth.
Thou hast set a bound which they shall not pass over; neither shall they return to cover the earth.
Psalms 103:7 At thy rebuke they shall flee: at the voice of thy thunder they shall fear.
Psalms 103:8 The mountains ascend, and the plains descend into the place which thou hast founded for them.
Psalms 103:9 Thou hast set a bound which they shall not pass over; neither shall they return to cover the earth.
Psalms 103:10 Thou sendest forth springs in the vales: between the midst of the hills the waters shall pass.
Psalms 103:11 All the beasts of the field shall drink: the wild asses shall expect in their thirst.
The verse centers on "thou", "hast", "bound", "shall", "pass", "over", and "neither". It is saying that the verse draws attention to "thou" and "hast", so its meaning should be read from those terms before moving to application.
The nearby context moves from verse 8's "The mountains ascend and the plains descend..." into verse 10's "Thou sendest forth springs in the vales...", so "thou" and "hast" belong inside that flow. In Psalms context, the local focus is worship, trust, the LORD's kingship, and covenant mercy.
A plain takeaway is to answer the verse's own emphasis on "thou" and "hast" with trust shaped by these words, not by a vague optimism outside the passage.