Musnad Abu Ya'la al-Mawsili 2:114

Ahmad ibn Ibrahim al-Dawraqi narrated to us, Abu Abd al-Rahman narrated to us, al-Layth ibn Sa'd Abu al-Harith narrated to us, from Yazid ibn Abd Allah ibn Usama ibn al-Had, Abu Uthman al-Walid ibn Abi al-Walid narrated to me, from Umar or Uthman ibn Abd Allah ibn Suraqa al-'Adawi, from Umar ibn al-Khattab, that he said: The Messenger of Allah (peace and blessings of Allah be upon him) said: "Whoever shades the head of a warrior, Allah will shade him on the Day of Resurrection. And whoever equips a warrior in the way of Allah with his equipment, then he has his reward. And whoever builds a mosque in which the name of Allah is mentioned, Allah will build for him a house in Paradise."