I don't think there is a natural link between Bede's Sparrow simile and Beowulf.
Bede's Ecclesiastical History is written by a Christian true-believer, steeped in the knowledge and beliefs of the Christian faith. Given the relatively short life of humans during Bede's lifetime, comparing man's life the image of a sparrow flying into and out of a hall, albeit with a short stop for warmth, was an apt comparison to man's journey on earth, which was short and largely devoid of comfort (other than that provided by religion). Bede's belief system is rooted in Christianity, the Beowulf poet's in a warrior culture that had not changed significantly in centuries.
Beowulf, despite its references to God and "Eternal Father", constantly reminds us that such references are essentially a proxy for fate and destiny. Although the Beowulf poet seems to be on the verge of internalizing conventional Christian beliefs, there are simply too many references in the poem to a manifestly non-Christian world view:
Each of us must expect an end/of worldly life;/let him who can, earn/fame before death; that's the finest thing. . . .
In one of many references to fate or destiny, Beowulf says "Wyrd often spares the undoomed earl, when his courage holds!" We can find many instances in which Christianity appears in the poem, but these appearances have more to do with Anglo-Saxon poliitical correctness than fully internalized beliefs.
Even though Beowulf clearly includes the theme of man's short life, and the poet includes Christian references, the Beowulf poet seems convinced that Wyrd governs the world of men. And, besides, he would probably advocate sacking Bede's convent to make sure sparrows had no respite.
Beowulf may be compared to Bede's sparrow in the sense of the metaphor the sparrow represents:
Suddenly a little bird flies in, a sparrow, ... So is the life of man. Clear enough itself, but before it, and after the end thereof, darkness; it may be, storm.
The sparrow represents the void at the beginning of life and the unknown at the end of life. A human's coming into life has no light on the place of origin, neither has a human's going out of life have a known destination. An unremembered void sends humans out and an undocumented void welcomes humans in at the beginning and then at the end of life. Like the sparrow, humans are "in at one door and then out at another. Where it came from none can say, nor whither it has gone."
I suppose there could be a broad comparison between Beowulf, who came into the lives of the Danes to save them, gives them a brief period of peace, and then leaves for his own kingship, and the sparrow that flies through the hall, briefly warm but then back into the winter, but it's a stretch. Better to compare Beowulf's search for glory, his success in battle, and his death itself as a life to the sparrow; they both have a perfect moment that ends.
I, personally, find the comparison in #3 above rather tenuous. I don't think Beowulf enters the mead hall like Bede' sparrow in any way. Beowulf does not enter seeking sanctuary and shelter. He comes deliberately to kill Grendel and to gain fame for himself. I personally think the main similarity is the religious one pointed out in #2.
Outside of the religious similarities between the two, I would suggest that Beowulf flies into the mead hall like Bede's sparrow. The sparrow, while seeking shelter from the cold, comes in, warms and leaves. Like the sparrow, Beowulf enters into Hrothgar's mead hall, does what needs to be done, and leaves as well.
They are most similar in that both emphasize the value of Christianity as an alternative to the paganism it replaced. Christianity gave the Old English something to look forward to after death (namely, eternal life in heaven with a loving God). In one Old English poem after another, heaven is seen as an alternative to the pain of existence divorced from God.