John Gill Commentary Luke 16:29

"But Abraham saith, They have Moses and the prophets; let them hear them." — Luke 16:29 (ASV)

Abraham said to him .
&c.] In reply to this his request:

they have Moses and the prophets ;
that is, their writings; which shows this man, and his five brethren, to be Jews; for to them were the oracles of God committed; and these had the writings of Moses and the prophets read to them every sabbath day; and is true, whether the contemporaries and immediate successors of the Pharisees are meant, or the ten tribes: and also shows, that one view of the parable, is to establish the authority of these writings; see (Luke 16:16Luke 16:17) and that it is a peculiar privilege to have them; and that they ought to be attended to and regarded;

let them hear them ;
for they testified concerning Christ, and concerning the sins of the Jews, and the calamities, both temporal and eternal, that should come upon them; and which, testimony was sufficient to leave them without excuse: and indeed, the word of God, read, explained, and heard, is the ordinary means of conversion, or of bringing men to faith and repentance.