Nay! I swear by the Day of Resurrection.
And nay! I swear by An-Nafs Al-Lawwamah.
Qatadah said,
"This means, I swear by both of these things."
This has also been reported from Ibn `Abbas and Sa`id bin Jubayr.
Concerning the Day of Judgement, it is well known what it is.
In reference to An-Nafs Al-Lawwamah, Qurrah bin Khalid reported from Al-Hasan Al-Basri that he said about this Ayah,
"Verily, by Allah, we think that every believer blames himself. He says (questioning himself),
`What did I intend by my statement What did I intend by my eating?
What did I intend in what I said to myself?'
However, the sinner proceeds ahead and he does not blame himself."
Ibn Jarir recorded from Sa`id bin Jubayr that he said concerning Allah's statement,
وَلَا أُقْسِمُ بِالنَّفْسِ اللَّوَّامَةِ
(And nay! I swear by An-Nafs Al-Lawwamah)
"He criticizes himself in good and bad."
Similar has been reported from `Ikrimah.
Ibn Abi Najih reported from Mujahid;
"He is sorry for what he missed (of good deeds) and he blames himself for it."
Allah said;
أَيَحْسَبُ الاِْنسَانُ أَلَّن نَجْمَعَ عِظَامَهُ