Then I will come to them from before them and from behind them and on their right and on their left, and You will not find most of them grateful [to You]."
("Because You have `Aghwaytani', surely, I will sit in wait against them (human beings) on Your straight path.") meaning, as You have sent me astray. Ibn `Abbas said that `Aghwaytani' means, "Misguided me." Others said, "As You caused my ruin, I will sit in wait for Your servants whom You will create from the offspring of the one you expelled me for." He went on,
The event relating to Sayyidna 'Adam (علیہ السلام) and the Shaytan has appeared earlier in Section four of Surah Al-Baqarah (Ma` ariful-Qur'an, English Translation, under verse 34). Some aspects of the subject have been covered in comments given there. Answers to some others are being given here.
How Long was the Respite given to Iblis?
It was exactly at the time Iblis was under the wrath of Allah, he made a prayer, a strange prayer indeed. He asked for a lease of life until the day of Resurrection. The words in which Allah Ta` ala answered the prayer, as they appear in this verse, are no more than: إِنَّكَ مِنَ الْمُنظَرِينَ (Respite is given to you). From these words, given the nature of the question and the answer, it can be understood that this respite was given until the Resurrection as asked by him. But, what is not stated in this verse clearly is whether the giving of respite mentioned here is until the Resurrection as asked by Iblis, or is for some other duration. But, in another verse, the words: إِلَىٰ يَوْمِ الْوَقْتِ الْمَعْلُومِ ﴿38﴾ (Till the day of the appointed time - 15:38) appear at this place which, on the surface, seem to suggest that the respite till the day of Qiyamah as asked by Iblis was not given. Instead, given to him was a respite till a particular time which is preserved in Divine knowledge. The outcome is that the prayer of Iblis was answered - though not completely. He was given respite till a particular time and not till the day of Resurrection or Qiyamah.
Whatever God has bestowed upon man in this world has been given for the purpose of eliciting his gratitude. But this is the very thing which man does not offer to his Lord. The reason for this is that Satan contrives to distort his feelings and steers him away from any expression of gratitude. It becomes evident from the story of Adam and Satan what the real criterion is for the judgement of one’s case. Man is being judged at the point where feelings of jealousy and pride develop in the human heart. In this world of trial it happens again and again that one man rises above another; sometimes one man receives a greater share of wealth and honour as compared to his fellow men. Sometimes, in a deal between two persons, it happens that one of them considers his discharging of the other’s legitimate rights as degrading to himself. On all such occasions man is being judged whether he responds positively or reacts negatively.
Uthmani text of the Madinah mushaf (King Fahd Complex). Translation: Saheeh International. Tafsir via Quran.com.