Musnad Ahmad 1153:344

Yunus narrated to us, Aban narrated to us, from Yahya, from Abu Salamah ibn Abd al-Rahman, that he entered upon Aisha while he was disputing over land. Aisha said: "O Abu Salamah, avoid the land, for the Messenger of Allah, peace and blessings of Allah be upon him, said: 'Whoever wrongs [another by taking] the measure of a span of land, it will be placed around his neck on the Day of Resurrection from seven earths.'"