The mention of "some of the scribes" likely pertains not to those from the Sadducean sect, who would find it difficult to acknowledge the Lord’s wisdom publicly, but rather to Pharisees who, despite their prior attempts to entrap the Lord alongside the Sadducees, may have savored the defeat of their rivals (see Matthew 22:34 and following). The Evangelist Mark indicates that a scribe who confronted the Lord later recognized the wisdom in His response to the Sadducees (Mark 12:23) and subsequently expressed his commendation (Mark 12:32). It is probable that this particular scribe, along with others who shared his sentiment, approached the Lord after His reply to the Sadducees, saying, "Master, you have spoken well," for the Lord effectively demonstrated through Scripture the truth of the resurrection, earning the respect of even His adversaries (Luke 20:40-44).
Turning to the Lord's inquiry regarding the Messiah—specifically, the identity of His Son—this aspect is presented in a manner consistent with Matthew and Mark's Gospels (see Matthew 22:41-46, Mark 12:35-37). Notably, "They dared not ask Him" indicates that following the Sadducees' embarrassment, a scribe had previously questioned Him about the most significant commandment in the law (Matthew 22:35-40, Mark 12:28-34). After this exchange, both Matthew and Mark, in their accounts, note that no one else was willing to pose further questions. Though Luke does not recount the discussion regarding the greater commandment with the scribe, he emphasizes that the Lord’s inquiry about the Christ was self-initiated rather than prompted by others, thus affirming their hesitance to engage Him further after His powerful response to the Sadducees concerning resurrection.
When questioning "How then is He Son unto him?" Luke does not elaborate on the impact this question had on the audience. However, this omission is compensated by the accounts of Matthew and Mark; Matthew records that no one could respond to Him, and Mark notes that the crowd listened eagerly to what He had to say.