“A single dirham has surpassed one hundred thousand dirhams.”
They said: How so?
He said: “A man possessed two dirhams and gave one of them in charity, while another man went to the abundance of his wealth, took one hundred thousand dirhams from it, and gave them in charity.”

Narrated by Aḥmad (no. 8929), al-Nasāʾī (no. 2527)—and this is his wording—by Ibn Khuzaymah (no. 2443), Ibn Ḥibbān (no. 3347), and al-Ḥākim (no. 1519), from the ḥadīth of Abū Hurayrah (may Allah be pleased with him).
Authenticated in Ṣaḥīḥ al-Jāmiʿ (no. 3606) and Ṣaḥīḥ al-Targhīb wa-l-Tarhīb (no. 883).

Brief Explanation of the Hadith

 In this ḥadīth there is a clear indication of the Prophet’s care (may Allah’s peace and blessings be upon him) in cultivating souls upon the principles of generosity and self-sacrifice (Ithār), while drawing attention to the fact that reward for giving is not measured by the abundance of wealth, but rather by what accompanies it of sincerity of intention, true reliance upon Allah, and trust in Him.
As for his statement (may Allah’s peace and blessings be upon him): “A single dirham has surpassed one hundred thousand dirhams,” it means that it surpassed them in reward and acceptance, not in amount. The Companions found this puzzling, since a single dirham is little whereas one hundred thousand is much. So the Prophet (may Allah’s peace and blessings be upon him) clarified to them the reason for this disparity: namely, that one of the two men possessed nothing but two dirhams, and he gave one of them in charity, thereby giving half of his wealth despite his need for it. As for the other man, he possessed abundant wealth, and he gave one hundred thousand in charity from the bulk of his property, without his charity affecting the foundation of his livelihood. Thus, the charity of the poor man was greater in reward than that of the wealthy man, because the poor man gives in charity despite his acute need for wealth, whereby perfect altruism is realized in his case. In contrast, the wealthy man gives his charity from the surplus of his wealth, so his charity does not embody the same degree of perfect altruism that is found in the charity of one who possesses little.
In the ḥadīth there is evidence that charity given at a time of need and hardship is greater in reward than the charity of the wealthy, even if the latter is multiplied many times over.
It also contains a subtle indication and an eloquent admonition from the Prophet, may Allah’s peace and blessings be upon him, aimed at stirring the feelings of the Companions and encouraging them to give in charity, by clarifying that true merit and superiority are not measured by the abundance of wealth, but rather by the sincerity of one’s giving and the magnitude of altruism involved.