My reading has been progressing at a glacial pace lately (hence the lack of any updates here), but a couple weeks ago I finished reading The Song of Roland for the first time. I found two Biblical allusions that my edition failed to note, although it comes extremely close to citing one of them.
In laisse 179, Charlemagne prays "to make the sun stand still for him in heaven, / hold back the night, let the day linger on" (lines 2450-2451). My edition has a footnote here referring the reader to a book that talks about "the story of Joshua as the model for this episode," yet it fails to identify "the model for this episode." It's Joshua 10:12-13: "At that time Joshua spoke to the LORD in the day when the LORD gave the Amorites over to the sons of Israel, and he said in the sight of Israel, 'Sun, stand still at Gibeon, and moon, in the Valley of Aijalon.' And the sun stood still, and the moon stopped, until the nation took vengeance on their enemies." In the Bible and in the poem, the sun stands still so that an army can continue its battle.
The other Biblical reference I found is in laisse 203. The day after the battle for which the sun stood still, the French army prepares to return to Rencesvals. "Then they mount up and ride with all their strength / on these long ways and on these great wide roads" (lines 2851-2852). That first line bears some resemblance to Isaiah 40:31: "They who wait for the LORD shall renew their strength; they shall mount up with wings like eagles; they shall run and not be weary; they shall walk and not faint." These are English translations, but both have "mount up," although one refers to mounting a horse and the other seems to refer to flying. Both also refer to strength. Isaiah says that "they who wait for the LORD shall renew their strength," and this is exactly what the French army does. Despite the exhausting battle the previous day (after which the army didn't even set a watch when they went to sleep), they can now "ride with all their strength" because of their faith in God.