The source of a sentence Zacharias Ursinus attributes to Justin Martyr

Ursinus:  Quemadmodum Justinus ait, Crede & ubique praesentem esse λόγον secundum substantiam, & singulari modo existere in proprio templo.  As Justin said, Believe both that the λόγος is everywhere present according to [his] substance and that [he] exists in a singular way in his own temple.  Zacharias Ursinus, Opera theologica (1612), vol. 2, p. 61 i.e. 65 (Responsio ad quintam Censuram, Quaestio XLIIX, Responsio).

Pseudo-Justin:  πίστευε καὶ παρεῖναι πανταχοῦ κατ' οὐσίαν τὸν λόγον καὶ κατ' ἐξαίρετον λόγον ὑπάρχειν ἔν τῷ οἰκείῳ ναῷ.  Crede etiam eum ubique secundum essentiam adesse et praecipua quadam ratione esse in proprio templo.  Believe that he is everywhere present according to [his] essence and that [he] is in a certain extraordinary way in his own temple.  Ἔκθεσις ὀρθῆς πίστεως/Expositio rectae fidei 15.  =Corpus apologetarum Christianorum saeculi secundi, 3rd ed., ed. de Otto, vol. 4 =tom. III pars I, Opera Iustini subditicia, Fragmenta pseudo-Iustini (Jena:  1880), 387B (p. 54).

     For more on the  Ἔκθεσις ὀρθῆς πίστεως or ὁμολογίας/Expositio rectae fidei, see Altaner, Patrology (London:  1960), pp. 369-370, 397-398 (where some of the literature on it is cited), and 114 (for the reference to the edition by de Otto); and Quasten, Patrology, vol. 1 (Utrecht:  1950), p. 207 (on the Expositio fidei seu De Trinitate, which falls under the "number of pseudo-Justinian works" contained in the manuscripts).  Very helpful in tracking this down was the version of the following in HTML online:  John S. Romanides, "Highlights in the debate over Theodore of Mopsuestia's Christology and some suggestions for a fresh approach," Greek Orthodox theological review 5:2 (1959/1960):  174 (40-185).
     With thanks to Lugene Schemper and Drew McGinnis for the diversion.

     The version in Ursinus without the ampersands:  Crede et ubique praesentem esse λόγον secundum substantiam, et singulari modo existere in proprio templo.