Mahāyāna and Hinayāna monks living together in 1st millenium India

In Paul Williams (2000) Buddhist Thought: A Complete Introduction page 97, it states:

We know from later Chinese sources, for example, that Chinese pilgrims to India found so-called non-Mahayana and Mahayana monks in the same monasteries.

No reference is given. Can anyone tell me:

  1. Which later Chinese sources say this?
  2. If they can work out what language their joint rituals, e.g. the pātimokkha recitations, were held in?
  3. Can anyone rule out Pali being that joint language, bearing in mind that Buddhaghosa was asked by Revata Thera to translate Sinhala commentaries into Pali for the benefit of mainlanders, according to the Cuḷavaṃsa?

Bikkhu Bodhi lives in a Mahayana monastery and would be able to give information on the answers to these questions:

I think it’s from Chinese pilgrims travel record like Faxian (Fa Hien) and Xuanzang (Hsuan Tsang). According to their record (if my memory is not mistaken), the Sthaviravada monks of same Vinaya lineage who reside in the same monastery in India that time either held Mahayana (called Mahayana-Sthavira) or non-Mahayana view and practice (called Hinayana-Sthavira). Because they are from the same lineage, they have the same patimokkha recitation and so that used the same language in their recitation.