I saw the Messenger of Allah (ﷺ) saying with fingers in the opening of his shirt:" If you had seen him trying to expand it, it will not expand."
Sahih Muslim Book 12, Hadith 97
← Previous Hadith (The miserly man) tries to expand it (the coat-of-mail) but it does not expand.

Sahih Muslim Book 12, Hadith 96 Next Hadith → . The similitude of a miserly man and the giver of charity is that of two persons with coats of mail over them; when the giver of charity intends to give charity, it expands over him (to much so) that the footprints are also obliterated. And when the miserly man intends to give charity, it contracts over him, and his hands are tied up to his collar bone, and every ring is fixed up to another. He (the narrator) said: I heard the Messenger of Allah (ﷺ) as saying: He would try to expand it. but he would not be able to do so.

Sahih Muslim Book 12, Hadith 98