Musannaf Ibn Abi Shayba 25:123

Ubayd Allah ibn Musa narrated to us, from Musa ibn Ubaydah, from Waqid ibn Muhammad ibn Zayd: That a man died and left behind wealth, and he bequeathed it in the way of Allah. The executor mentioned that to Umar ibn al-Khattab. He said, "Give it to the workers of Allah." He asked, "And who are the workers of Allah?" He said, "The pilgrims of the House of Allah."