Tafsir Ibn Kathir -> Surah Ar-Rum -> The Different Stages of Man

Here Allah points out how man passes through different stages of creation, one phase after another. He is originally created from dust, then from a Nutfah, then from a clot, then from a lump of flesh. Then he becomes bones, then the bones are clothed with flesh, then the soul is breathed into him. Then he emerges from his mother's womb, weak and thin and powerless. Then he grows up little by little, until he becomes a child, then he reaches the stage of puberty, then he becomes a young man, which is strength after weakness. Then he starts to get older, reaching middle age, then old age and senility, weakness after strength, so he loses his resolve, power of movement and ability to fight, his hair turns grey and his characteristics, both inward and outward, begin to change. Allah says:

﴿ثُمَّ جَعَلَ مِن بَعْدِ قُوَّةٍ ضَعْفاً وَشَيْبَةً يَخْلُقُ مَا يَشَآءُ﴾

(then after strength gave (you) weakness and grey hair. He creates what He wills.) He does whatsoever He wills and controls His servants in whatever way He wants.

﴿وَهُوَ الْعَلِيمُ الْقَدِيرُ﴾

(And He is the All-Knowing, the All-Powerful.)

﴿وَيَوْمَ تَقُومُ السَّاعَةُ يُقْسِمُ الْمُجْرِمُونَ مَا لَبِثُواْ غَيْرَ سَاعَةٍ كَذَلِكَ كَانُواْ يُؤْفَكُونَ - وَقَالَ الَّذِينَ أُوتُواْ الْعِلْمَ وَالإِيمَـنَ لَقَدْ لَبِثْتُمْ فِى كِتَـبِ اللَّهِ إِلَى يَوْمِ الْبَعْثِ فَهَـذَا يَوْمُ الْبَعْثِ وَلَـكِنَّكُمْ كُنتمْ لاَ تَعْلَمُونَ - فَيَوْمَئِذٍ لاَّ ينفَعُ الَّذِينَ ظَلَمُواْ مَعْذِرَتُهُمْ وَلاَ هُمْ يُسْتَعْتَبُونَ ﴾

(55. And on the Day that the Hour will be established, the criminals will swear that they stayed not but an hour -- thus were they ever deluded.) (56. And those who have been bestowed with knowledge and Faith will say: "Indeed you have stayed according to the decree of Allah, until the Day of Resurrection; so this is the Day of Resurrection, but you knew not.'') (57. So, on that Day no excuse of theirs will avail those who did wrong, nor will they be allowed to return to seek (Allah's) pleasure.)