A.T. Robertson Commentary Acts 16:40

"And they went out of the prison, and entered into [the house] of Lydia: and when they had seen the brethren, they comforted them, and departed." — Acts 16:40 (ASV)

Into the house of Lydia (προς την Λυδιαν). No word in the Greek for "house," but it means the house of Lydia. Note "the brethren" here, not merely Luke and Timothy, but other brethren now converted besides those in the house of the jailor. The four missionaries were guests of Lydia (verse 15) and probably the church now met in her home.

They departed (εξηλθαν). Paul and Silas, but not Luke and Timothy. Note "they" here, not "we." Note also the -αν ending instead of -ον as above. The movements of Timothy are not perfectly clear till he reappears at Beroea (17:15). It seems unlikely that he came to Thessalonica with Paul and Silas since only Paul and Silas obtained security there (17:9) and were sent on to Beroea (17:10). Probably Timothy was sent to Thessalonica from Philippi with gifts of which Paul spoke later (Php 4:15f.). Then he followed Paul and Silas to Beroea.