قَدْ خَسِرَ ٱلَّذِينَ كَذَّبُوا۟ بِلِقَآءِ ٱللَّهِ ۖ حَتَّىٰٓ إِذَا جَآءَتْهُمُ ٱلسَّاعَةُ بَغْتَةً قَالُوا۟ يَٰحَسْرَتَنَا عَلَىٰ مَا فَرَّطْنَا فِيهَا وَهُمْ يَحْمِلُونَ أَوْزَارَهُمْ عَلَىٰ ظُهُورِهِمْ ۚ أَلَا سَآءَ مَا يَزِرُونَ
10:46.
2:168.
Important Words:
فرطنا (our neglecting) is derived from فرّط (farrata) which again is derived from فرط (farata) which means, he went before or preceded. فرط منه الکلام means, the speech or the words issued from him hastily before reflection. فرط علیه means, he acted hastily and unjustly towards him. فرّطه (farratahu) means, he made him to precede; or he made him to be before, or beforehand or first or foremost. فرطه also means, he sent it before, himself remaining behind it. فرط عنه means, he left or forsook him; or he abstained or desisted from it. فرط فیه means, he neglected it or he was remiss with respect to it; or he preferred backwardness in it; or he failed to do, or fell short of doing, what he ought to have done with respect to it. افرط فی الامر means, he exceeded due bounds or just limits in the matter. Thus تفریط (from فرط) has generally come to mean, "falling short of" and إفراط(from افرط) "exceeding proper limits" (Lane & Aqrab).
الا (surely) originally denotes an interrogation respecting a negative, or a wish or reproof, or the asking for or requiring a thing. It is also used as an inceptive particle giving the sense of "now" or "why". It also means, verily, truly or surely (Lane).
Commentary:
The pronoun in فیھا (this) may refer to the "Hour" mentioned above. In that case, "neglecting this Hour" would mean that disbelievers never believed that the Hour would come and never gave it a thought; or it may refer to الدنیا (the earth) or to حیاتنا الدنیا (our present life) occurring in 6:30 above. In this case, the sentence would mean that they acted negligently during their life on this earth.
The words, they shall bear their burdens on their backs, are intended to hint that their burdens would be exceedingly heavy.
10:46.
2:168.
The verse means that their burdens would be exceedingly heavy.