Acts 17:2

2 and according to the custom of Paul, he went in unto them, and for three sabbaths he was reasoning with them from the Writings,

Acts 17:2 Meaning and Commentary

Acts 17:2

And Paul, as his manner was, went in unto them
To the Jews in their synagogue; for though the Jews had put away the Gospel from them, and the apostle had turned to the Gentiles; yet he still retained a great affection for his countrymen the Jews, and as often as he had opportunity, attended their synagogues, in order to preach the Gospel to them;

and three sabbath days reasoned with them out of the Scriptures:
that is, out of the Old Testament, concerning the Messiah, the characters of him, the work that he was to do, and how he was to suffer and die for the sins of men; and this he did three weeks running, going to their synagogue every sabbath day, when and where the Jews met for worship; and made use of books, which they allowed of, and of arguments they could not disprove.

Acts 17:2 In-Context

1 And having passed through Amphipolis, and Apollonia, they came to Thessalonica, where was the synagogue of the Jews,
2 and according to the custom of Paul, he went in unto them, and for three sabbaths he was reasoning with them from the Writings,
3 opening and alleging, `That the Christ it behoved to suffer, and to rise again out of the dead, and that this is the Christ -- Jesus whom I proclaim to you.'
4 And certain of them did believe, and attached themselves to Paul and to Silas, also of the worshipping Greeks a great multitude, of the principal women also not a few.
5 And the unbelieving Jews, having been moved with envy, and having taken to them of the loungers certain evil men, and having made a crowd, were setting the city in an uproar; having assailed also the house of Jason, they were seeking them to bring [them] to the populace,
Young's Literal Translation is in the public domain.