Commentary on the Diatessaron 21.21 — as quoted by Pitre (p 137); translation: Carmel McCarthy, Saint Ephrem's Commentary on Tatian's Diatessaron (Oxford, 1993)
[The fact] that 'they sealed the tomb' (Matt 27:66) was in [the Lord's] favour…He took the body out from the tomb, although it was sealed, and the seal of the tomb witnessed in favour of the seal of the womb that had borne him. For it was when the virginity was sealed that the Son emerged alive from within her…
No freely usable English translation of this passage is online, so the note keeps Pitre's quotation and links to the full text. Translation: Carmel McCarthy, Saint Ephrem's Commentary on Tatian's Diatessaron (Oxford, 1993), as quoted by Pitre.
Why Pitre cites it
'The seal of the tomb witnessed in favour of the seal of the womb that had borne him.' Pitre's key text for the virgin birth as a sign of the resurrection.