Musnad Ahmad 1153:574

Abu al-Yaman narrated to us, he said: Isma'il ibn 'Ayyash narrated to us, from Hisham ibn 'Urwah, from his father, from 'Aishah, she said: The Messenger of Allah, may Allah bless him and grant him peace, said: "Indeed, Allah, the Almighty and Majestic, and His angels, peace be upon them, send blessings upon those who join the rows. And whoever fills a gap, Allah raises him a degree by it."