Psalm 49/Notes/Grammar.v. 9.24805

The MT's נפשם/"their soul" (pl.) could reflect the (erroneous, momentary) reading of אח as "brother" instead of אח as the interjection "surely" (i.e., the alternatively (or carelessly) spelled אַךְ; note that eight MSS have אַךְ here instead of אָח; cf. v. 16, which deals with the issue of redemption, uses the root פדה, and features אַךְ: "But/אַךְ God will redeem me from the realm of the dead..." [NIV]). So, "their soul" would refer to the soul(s) of this brother and the איש he is trying to redeem (per such reading). In other words, the ransom for both of them is too costly. The pl. form of נפש would not be necessary, as the singular could be used in contexts where the plural is meant (e.g., נפשנו תחתיכם; Josh 2:14). Alternatively, the MT's נפשם/"their soul" (pl.) could refer to the individuals (pl.) from vv. 6-7, who trust in their wealth and boast of their riches. But the switch to singular forms in vv. 9b, 10, 11 makes it unlikely. Again, the singular suffix here is preferable. On a separate note, Raabe observes that in v. 9 "both cola exhibit final rhyme (-am)."