אָ֗ח לֹא־פָדֹ֣ה יִפְדֶּ֣ה אִ֑ישׁ לֹא־יִתֵּ֖ן לֵאלֹהִ֣ים כָּפְרֽוֹ׃
No man can by any means redeem his brother, nor give to God a ransom for him—
Rashi on Psalms
A brother cannot ransom his brother with money because the ransom of their soul is dearer than any possession. Therefore, perforce, his redemption is forever unattainable.