Sayyiduna Abdullah bin Umar (may Allah be pleased with them both) was asked about a man who traded with someone else's goods and went against (the owner's instructions). Sayyiduna Abdullah bin Umar (may Allah be pleased with them both) said: "He is liable for it, and if he made a profit, the profit goes to the owner of the wealth."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب القراض / 11619