Musnad Ahmad Hadith 19624

It is narrated from Abu Musa (may Allah be pleased with him) that a Muslim is like a building for another Muslim, one part of which strengthens the other. And the example of a good companion is like that of a perfume seller: even if he does not bring his bottle of perfume near you, its fragrance will still reach you. And the example of a bad companion is like that of a blacksmith’s furnace: even if it does not burn you, its heat and flames will still reach you. And a trustworthy treasurer is one who, when he is instructed regarding something, fulfills it completely, perfectly, and with happiness of heart, so that what the donors have ordered to be given reaches those for whom it is intended.