Cite the scanned version of the original dicionary like this:
Bosworth, Joseph. "be-æftan." An Anglo-Saxon Dictionary: Based on the Manuscript Collections of the Late Joseph Bosworth. Ed. Thomas Northcote Toller. Oxford: Clarendon Press, 1898. 7.
.Add:I.prep. (1) local, (a) in contrast with before :-- Hé hæfde þriddan dǽl his firde beæftan him, Ors. 1, 12; S. 52, 33. (b) in contrast with advance along with :-- Hé forlét hundeahtatig þúsenda beæftan him, Ors. 2, 5; S. 78, 17: 5, 12; S. 240, 3. (2) figurative :-- Ic forlǽte mínne ágene wyllan beæftan mé for nytnesse mínra freónda voluntatem meam postpono utilitati proximorum, Gr. D. 259, 16. II.adv. (1) behind, (a) in contrast with before, (α) local :-- Tó þǽm folce þe þǽr beæftan wæs, Ors. 1, 12; S.