In The Name of Allaah, The Most Merciful, The Bestower of Mercy.
Allaah [The Most High] said:
وَإِذَآ أَذَقۡنَا ٱلنَّاسَ رَحۡمَةً۬ مِّنۢ بَعۡدِ ضَرَّآءَ مَسَّتۡہُمۡ إِذَا لَهُم مَّكۡرٌ۬ فِىٓ ءَايَاتِنَاۚ قُلِ ٱللَّهُ
أَسۡرَعُ مَكۡرًاۚ إِنَّ رُسُلَنَا يَكۡتُبُونَ مَا تَمۡكُرُونَ
And when We let mankind taste of mercy after some adversity has afflicted them, behold! They take to plotting against Our Ayat [proofs, evidences, verses, lessons, signs, revelations, etc.]! Say: “Allah is more Swift in planning!” Certainly, Our Messengers (angels) record all of that which you plot. [Soorah Yunus: Aayah 21]
[وَإِذَآ أَذَقۡنَا ٱلنَّاسَ رَحۡمَةً۬ مِّنۢ بَعۡدِ ضَرَّآءَ مَسَّتۡہُمۡ – And when We let mankind taste of mercy after some adversity has afflicted them] – such as health after illness, wealth after [a state of] poverty, safety after [a state of] fear, they forget the adversity that afflicted them and do not thank Allaah for the ease and mercy [they receive]; rather they continue in their transgression and plotting. And due to this reason Allaah [The Most High] said: [ۡ إِذَا لَهُم مَّكۡرٌ۬ فِىٓ ءَايَاتِنَا – behold! They take to plotting against Our Ayat (proofs, evidences, verses, lessons, signs, revelations, etc.)]– Meaning: They hasten towards falsehood in order to falsify the truth by way of it.
[قُلِ ٱللَّهُ أَسۡرَعُ مَكۡرًاۚ – Say: Allah is more Swift in planning]– Meaning: Evil plotting encompasses only those who make it. Their [evil] aims will be thrown back at them and they will not be safe from the consequences; rather the angels write down what they used to do and Allaah will call them to account, then Allaah will recompense them for it with a full recompense [i.e. as they deserve without any injustice, decrease or increase].
[Source: An Excerpt from ‘Tayseer Al-Kareem Ar-Rahmaan Fee Tafseer Kalaam Al-Mannaan of Imaam Sadi (rahimahullaah)’. Slightly paraphrased]