40. The word 'day' in the above verse has been used either in the usual sense
of the twenty-four hour unit of time, or in a more general sense of 'period'
of time such as in the following verses of the Qur'an:
Verily a Day in the sight of your Lord is like a thousand years of your reckoning
(al-Hajj 22: 47).
The angels and the Spirit ascend unto Him on a Day the measure of which is fifty
thousand years
(al-Ma'arij 70: 4). For further explanation see
(Fussilat 41, nn. 12-15.)