وَأَمَّا مَنْ خَفَّتْ مَوَازِينُهُ فَأُمُّهُ هَاوِيَةٌ
And as for the one whose balances are light, the abyss will be that person’s refuge. (101:8–9)
Thaqulat in the first case is balanced against khaffat in the second. The repeated ammā … fa pattern gives parallel grammatical form to opposed outcomes.
Fa-ummuhu hāwiyah should not be read as an ordinary claim about a biological mother. The expression figuratively identifies the person’s destination or refuge with the abyss, which the following verse explains.