﴿17﴾ كَانُوا قَلِيلاً مِّنَ اللَّيْلِ مَا يَهْجَعُونَ
(shāri‘), the God fearing believer whose hear is purified devotes the dawn time to invoking God Almighty, the Oft-Forgiving, for forgiveness. As some Qur'anic exegets maintain, the blessed Verse refers to the point that the God fearing are supposed to repeatedly invoke God Almighty for forgiveness following their nightly prayers unless they be deceived by formal worship imagining that they have attained to the exalted state of being close to God Almighty consigning to oblivion the Qur'anic Verse “Indeed Allah accepts [prayers] from the God fearing.”
Imam Sādiq (AS) said: “The best time for invocation to God Almighty is dawn, since Allah says: ‘And at dawn, they were invoking [Allah] for forgiveness.’” Regarding the blessed Verse in question, he said: “It refers to invoking God Almighty seventy times for forgiveness in odd (witr) and night prayers.” According to a Prophetic tradition quoted in Durr al-Manthūr: “Late night is more desirable to me than early night for night prayers, since God Almighty says: ‘The God fearing invoke God Almighty for forgiveness at dawn.’” It is also narrated from Imam Sādiq (AS): “The good-doers who are the people of Paradise invoke God Almighty seventy times for forgiveness in their odd prayers at dawn.”
The blessed Verse 19 enumerates another attribute of the God fearing saying that they determine certain portions for the poor in their property thereby they take the poor as their partners in their property. The Arabic word sā'il is applied to a poor man who expresses his poverty asking the rich to provide him with what is due to him. The word mahrūm is applied to a gentleman whose continence impedes him from expressing his poverty and dire state.
 Mustadrak, vol. 5, p. 200.  Tahdhīb, vol. 2, p. 130.  Durr al-Manthūr, vol. 6, p. 113.  Majma‘ al-Bayān, under the blessed Verses in question.