Ṣaḥīḥ al-Bukhārī & Ṣaḥīḥ Muslim

Abu Hurayrah (may Allah be pleased with him) reported that the Prophet (may Allah's peace and blessings be upon him) said: “The example of a miser and a generous person is that of two men wearing two iron cloaks covering their breasts up to their collar bones. Whenever the generous person gives something away, his iron cloak expands until it becomes so wide that it will cover his fingertips and obliterate his traces.

But whenever the miser thinks of spending, every ring of the iron cloak sticks to its place (against his body) and he tries to expand it, but it does not expand.”