A-borgian

According to the Old English Dictionary:

a-borgian

p. ode; pp. od To be surety, to undertake for, to assign, appoint; fidejubere :-- Gif he nite hwá hine aborgie; hæfton hine if he know not who will be his borh, let them imprison [lit. have, detain] him, L. Ath. i. 20; Th. i 210, 8. a-borgian