Musannaf Ibn Abi Shaybah 35808 — Racing and wagers

It is narrated from Bakr that two men saw a deer while they were both in the state of ihram. They competed over it and made a wager, and one of them struck it with a stick and broke it. Then they both came to Sayyiduna Umar (may Allah be pleased with him), and Sayyiduna Abd al-Rahman bin Awf (may Allah be pleased with him) was sitting beside him. Sayyiduna Umar (may Allah be pleased with him) asked Sayyiduna Ibn Awf (may Allah be pleased with him), "What is your opinion?" Sayyiduna Ibn Awf (may Allah be pleased with him) said, "This is gambling, even if it was a contest."