Shuba reported,

Ibn Abbas, whenever he performed the major ritual washing after sexual impurity, would pour water with his right hand onto his left hand seven times, then wash his private parts. One time he forgot how many times he had poured, so he asked me, "How many times did I pour?"I replied, "I don't know."He said, "May you lose your mother! What kept you from keeping count?"Then he would perform ablution as he did for prayer, then pour water over his skin, and then say, "This is how the Messenger of Allah ﷺ used to purify himself."

حدثنا حسين بن عيسى الخراساني حدثنا ابن أبي فديك عن ابن أبي ذئب

عن شعبة قال

إن ابن عباس كان إذا اغتسل من الجنابة يفرغ بيده اليمنى على يده اليسرى سبع مرار ثم يغسل فرجه فنسي مرة كم أفرغ فسألني كم أفرغت فقلت لا أدري فقال لا أم لك وما يمنعك أن تدري ثم يتوضأ وضوءه للصلاة ثم يفيض على جلده الماء ثم يقول هكذا كان رسول الله ﷺ يتطهر