I know that it is in Pāli. Eventually someone will find you that. It is a linguistic formula, if I remember right, to do with idappaccayatā in Pāli scriptures.
But I do know where it is in the Saṃyuktāgama, it is in the Sarvāstivāda-parallel to the Paccayasutta (SA296 parallel SN12.20):
云何為因緣法？謂此有故彼有， 謂緣無明行，緣行識，[…]
And what is the pratītyasamutpada Dharma? To say, “this is, because that is,” to say, “conditioned by ignorance, there are the activities, conditioned by the activities there is the consciousness,” […]
I wonder if 謂 is translating something like “iti”? That just came to mind. I wonder what Venerables @vimalanyani or @sujato might think of that notion. Or @wkhtfb, who I understand reads Chinese and might be of insight here. “Iti,” if I am not misinformed in presenting it this way, is a sort of “quotation mark” for oral literature. I am wondering of the Prākrit this Chinese was translated form might have had some kind of “iti” idiom for 謂, which shows up near-constantly in many SA texts. The presentation @Javier linked us to here, on the orality of Prākrit literature and it’s Sanskritization, had a section to-do with “iti” in the Pāli recension of buddhavacana.
Actually, I think I found the Pāli while writing this post. From SN12.37 Natumhasutta transl V Sujāto:
‘iti imasmiṃ sati idaṃ hoti, imassuppādā idaṃ uppajjati;
imasmiṃ asati idaṃ na hoti, imassa nirodhā idaṃ nirujjhati, yadidaṃ— avijjāpaccayā saṅkhārā; saṅkhārapaccayā viññāṇaṃ … pe … […]
‘When this exists, that is; due to the arising of this, that arises.
When this doesn’t exist, that is not; due to the cessation of this, that ceases. That is: Ignorance is a condition for choices. Choices are a condition for consciousness. … […]