The sparrow finds home a while the swallow finds a nest. Both birds find homes and nests on the LORD'S Altars (plural), not altar.
Even the sparrow has found a home, And the swallow a nest for herself, Where she may lay her young -- Even Your altars, O LORD of hosts, My King and my God.
According to the law this is not possible due to the ordinance of the morning and evening sacrifice. Therefore both altars, golden and brazen are not available as a nesting place for birds.
For the Brazen altar
a) A fire burns on this altar perpetually:
'A fire shall always be burning on the altar; it shall never go out.
b) There is a perpetual morning and evening sacrifice.
"Now this is what you shall offer on the altar: two lambs of the first year, day by day continually. "One lamb you shall offer in the morning, and the other lamb you shall offer at twilight.
For the golden altar- Altar of Incense:
c) Incense burns on this altar perpetually.
"Aaron shall burn on it sweet incense every morning; when he tends the lamps, he shall burn incense on it.
8) "And when Aaron lights the lamps at twilight, he shall burn incense on it, a perpetual incense before the LORD throughout your generations
d) It is close to the holiest of holies and therefore the poop and urine of birds would defile it. The law considers excrement as an unclean thing.
"...you shall dig with it and turn and cover your refuse. "For the LORD your God walks in the midst of your camp... therefore your camp shall be holy, that He may see no unclean thing among you, and turn away from you.
e) Swallows build their nests on vertical surfaces. The altar is not a vertical surface.
Today, barn swallows almost always build nests on...structures that have a ledge that can support the nest, a vertical wall to which it can be attached.
Literally or contextually, how can I make sense of this verse in light of the ordinances of the altar and the vertical surfaces that Swallows require for their nests.