(a) Sayyidah Aishah (may Allah be pleased with her), describing the prayer of the Messenger of Allah (peace and blessings be upon him), said that the Messenger of Allah (peace and blessings be upon him) would recite the tashahhud between every two rak'ahs.
(b) In the narration of Husayn bin Dhakwan al-Mu'allim in Sahih Muslim, she said: He (peace and blessings be upon him) used to say: "In every two rak'ahs there is the tashahhud."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصلاة / 2797