What are the Biblical allusions in Ode To a Nightingale?

The main Biblical allusion in Ode to a Nightingale is in stanza VII, when Keats writes "through the sad heart of Ruth, when, sick for home, / She stood in tears amid the alien corn" (line 66-67). This refers to the story of Ruth in The Bible, who stayed with her mother-in-law Naomi after they were both widowed (at the time, widows had no means of caring for themselves or others; Naomi encouraged Ruth to go, leave her, and marry again). She was a stranger in a strange land because Naomi went back to her original home, and Ruth was from elsewhere. Thus the image of Ruth "sick for home" - homesick. "She stood in tears amid the alien corn" alludes to the part of Ruth's story where she went behind the harvesters, picking what was left. The practice at the time was to go through the field only once, and whatever was left would be left for widows and orphans and others unable to care for themselves to come through and gather so they would have something to sustain themselves. Hope that helps.