This incident is reported in Volume 2 of Ihya, under chapter "Etiquettes of Marriage", under the heading "Husband duties towards his wife".
Here are 2 Paragraphs (abriged) before the incident:
And know that to have patience at the time when the wife gets angry
and when she gives trouble is actually following the Prophet() in good
treatment with her. It is not merely to restrain oneself from
inflicting troubles on the wife...
The wives of Prophet argued before him sometimes. Once a wife of
Prophet() did something wrong and her mother got angry but the
Prophet() said "leave her for she does more than this"!
وجرى بينه وبين عائشة كلام حتى أدخلا بينهما أبا بكر رضي الله عنه حكما
واستشهده فقال لها رسول الله صلى الله عليه وسلم تكلمين أو أتكلم فقالت
بل تكلم أنت ولا تقل إلا حقا فلطمها أبو بكر حتى دمى فوها وقال يا عدية
نفسها أو يقول غير الحق فاستجارت برسول الله صلى الله عليه وسلم وقعدت
خلف ظهره فقال له النبي صلى الله عليه وسلم لم ندعك لهذا ولا أردنا منك
Basically: Prophet and Aisha had a dispute (maybe this) & Abu
Bakr was brought in as a Judge! When Abu Bakr came, Prophet said to
Aisha "will you speak or I should speak" and she said "you speak but
tell clearly/truth" upon which Abu Bakr got angry & hit her. And then
Prophet said to Abu Bakr "we didn't call you for this".
Al-Hafidh al-Iraqi (and later it was finished by al-Iraqi's student Ibj Hajar Asqalani) was one of many, who wrote monumental commentaries on Ihya. According to him, the hadith with the exact wording, is not Saheeh (either Hassan or Daeef), and it is found in:
- Imam Tabarani's Al-Mu'jam Al-Awsat
- Khatib Baghdadi's Tareekh
Another similar question.