Adam Clarke on Psalms 49:5

The iniquity of my heels - Perhaps עקבי akebai, which we translate my heels, should be considered the contracted plural of עקבים akebim, supplanters. The verse would then read thus: "Wherefore should I fear in the days of evil, though the iniquity of my supplanters should compass me about." The Syriac and Arabic have taken a similar view of the passage: "Why should I fear in the evil day, when the iniquity of my enemies compasses me about." And so Dr. Kennicott translates it.