Duthūr is the plural of dather—with the dāl pronounced openly and the thāʾ left quiescent—and it means abundant wealth.

Explanation
This hadith shows the superiority of a specific form of remembrance that is linked to a particular deed. As noted earlier, some adhkār are unrestricted while others are restricted; this is one of the restricted forms.

Abū Hurayrah reported that the poor Emigrants came to the Prophet (peace and blessings be upon him) complaining: “The wealthy have outstripped us. They pray as we pray and fast as we fast, yet they possess extra wealth with which they give charity, perform ḥajj and ʿumrah, and strive in jihād.” The Prophet (peace and blessings be upon him) then guided them, saying, “Shall I not tell you something which, if you do it, none who has preceded you will surpass you and by which you will outstrip those who come after you?” They replied, “Indeed, O Messenger of Allah.” He said, “After every obligatory prayer recite tasbīḥ, taḥmīd, and takbīr thirty-three times,” meaning one says “Subḥān Allah,” “al-ḥamdu lillāh,” and “Allāhu akbar” thirty-three times each—making ninety-nine in all.

The poor Companions carried this out, but when the wealthy heard of it they did the same, so the two groups were now equal in this remembrance. The poor returned to the Messenger of Allah (peace and blessings be upon him) and said, “O Messenger of Allah, our affluent brothers have heard what we did and done the same.” It was as though they sought some other deed unique to them, but he answered, “That is the bounty of Allah; He grants it to whom He wills.”

Among the lessons of this hadith are, first, the Companions’ eagerness—may Allah be pleased with them—to compete in righteous works; each of them wanted to excel the others.

Another benefit derived from this narration is that this remembrance—“Subḥān Allah, al-ḥamdu lillāh, Allāhu akbar”