Musnad Abu Ya'la al-Mawsili 159:50

Suwayd narrated to us, from Malik, from Abu al-Zinad, from al-A'raj, from Abu Hurayrah, that the Messenger of Allah (may Allah bless him and grant him peace) said: "The procrastination of the wealthy is injustice. And if one of you is referred to a solvent person, then let him follow [the referral]."