Cite the scanned version of the original dicionary like this:
Toller, T. Northcote, and Joseph Bosworth. "pyndan." An Anglo-Saxon Dictionary: Based on the Manuscript Collections of the Late Joseph Bosworth : Supplement. Oxford: Clarendon Press, 1921. 682.
to shut up, dam. [Moni punt hire word uorte leten mo ut, as me deþ water and ter mulne cluse, A. R. 72, 10. To pynde includere, Cath. Angl. 280.] v. for-, ge-pyndan; pynding.