Allah concludes surah al-Hijr [15] by saying:
[وَاعْبُدْ رَبَّكَ حَتَّىٰ يَأْتِيَكَ الْيَقِينُ]
And worship your Lord until certainty comes to you [99]
In his commentary on this ayah, al-Qurtubi wrote:
[كان عمر بن عبد العزيز يقول : ما رأيت يقينا أشبه بالشك من يقين الناس بالموت ثم لا يستعدون له ; يعني كأنهم فيه شاكون]
‘Umar ibn ‘Abd al-‘Aziz used to say: I have never seen a “certainty” that looked more like doubt than people being certain of death and then not preparing for it!
That is to say, they acted as if they had doubts about whether it would happen or not.
[Jaami’ li-Ahkam al-Qur’an 10/59]
