Majma al-Zawaid 12105 — Further reports on following the ways of those

Sayyiduna Abdullah bin Abbas (may Allah be pleased with them both) narrates that the Prophet (peace and blessings be upon him) said: "You will surely follow the ways of those before you, span for span, dhira' for dhira' (the length from the tip of the middle finger to the elbow is called a 'dhira'') and ba' for ba' (the span of both outstretched arms is called a 'ba''), so much so that if one of them entered a lizard's hole, you too would enter it, and if one of them had intercourse with his mother, you too would do so."
Al-Bazzar recorded it, and its narrators are thiqat (trustworthy).