ووصينا اﻻنسان بوالديه حملته أمه وهنا على وهن
And We have enjoined on man (to be dutiful and good) to his parents. His mother bore him in weakness and hardship upon weakness and hardship,
Mujahid said: "The hardship of bearing the child.''
Qatadah said: "Exhaustion upon exhaustion.''
Ata' Al-Khurasani said: "Weakness upon weakness.''
وفصاله في عامين
and his weaning is in two years,
means, after he is born, he is breastfed and weaned within two years.
This is like the Ayah,
والولدت يرضعن أولدهن حولين كاملين لمن أراد أن يتم الرضاعة
The mothers shall give suck to their children for two whole years, for those who desire to complete the term of suckling. (2:233)
On this basis, Ibn Abbas and other Imams understood that the shortest possible period of pregnancy was six months, because Allah says elsewhere:
وحمله وفصله ثﻼثون شهرا
and the bearing of him, and the weaning of him is thirty months (46:15).
Allah mentions how the mother brings the child up, and how she gets tired and suffers stress from staying up with the child night and day, to remind the son of her previous kind treatment of him.
This is like the Ayah,
وقل رب ارحمهما كما ربيانى صغيرا
and say: "My Lord! Bestow on them Your mercy as they did bring me up when I was young.'' (17:24)
Allah says here:
أن اشكر لي ولوالديك إلي المصير
give thanks to Me and to your parents. Unto Me is the final destination.
means, `I will reward you most generously for that.'