The Hebrew sharir appears only once (hapax legomenon) in Job 40:16, describing the power of the great beast Behemoth: 'his strength is in his muscles.' The word denotes the sinew or muscle that provides physical power, derived possibly from the root meaning to be firm or hard. Its single usage in the context of Behemoth makes it part of God's great speech from the whirlwind — a declaration of the scale and power of creation that dwarfs human strength.
In the YHWH speeches (Job 38–41), God challenges Job with images of uncontrollable creation: storm, stars, and now Behemoth — whose sharir (muscles/sinews) surpass human capacity. The theological point is the incomparable power of God who created and controls such creatures. Human strength is finite; God's is infinite. Paul echoes this: 'God chose the weak things of the world to shame the strong' (1 Corinthians 1:27). Spiritual power comes not from human sharir but from the Spirit of God.