John Gill Commentary Acts 15:33

"And after they had spent some time [there], they were dismissed in peace from the brethren unto those that had sent them forth." — Acts 15:33 (ASV)

And after they had stayed there a space
How long is not certain; the Arabic version renders it "a year"; and it is probable enough, they might stay there so long, until things were thoroughly settled, which had been thrown into great disorder and confusion by the pleaders for circumcision:

they were let go in peace ;
that is, they were dismissed, and went away with the leave and consent of the church; who thanked them for their service and good offices, and wished them peace, prosperity, happiness (both in soul and body), and great success in their ministrations wherever they went: and as they were dismissed in peace, they left the church in perfect peace; because the controversy about circumcision, which had been raised among them, had been ended; and the members of the church were agreed in their sentiments and heartily united in their affections to one another:

And thus Judas and Silas were honourably dismissed

from the brethren ,
at Antioch, to the Apostles ,
at Jerusalem; the Alexandrian copy, and Beza's ancient copy, the Vulgate Latin, and Ethiopic versions, read, "to them that sent them"; and so include, with the apostles, the elders, and brethren at Jerusalem, who wrote the letter to the church at Antioch, and sent it by them; and it was proper that they should return to them, and give them an account of the success of it, how it was received, and what good it had done.