Why does macbeth question banquo about where he is going prior to dinner?

The reason Macbeth question Banquo about where he is going prior to dinner:

Banquo is a general in the Scottish army who is with Macbeth when the three witches make their prophecy. Though he considers the three witches evil, their prophecy that not he but his children will be the King make him and his son Fleance the targeted enemies of Macbeth.

Macbeth has organized a feast and enquires of Banquo where he was going prior to dinner as he intends to send the three murderers after him and his son to kill both of them and clear obstacles in his path to fulfill his ambitions. Though he tells him to be there and fail not the feast, his plan contradicts his spoken word.

When Macbeth enquires of him he is quite suspicious that Banquo knows he has killed the king. Banquo tries to hide his fears regarding Macbeth being unfair. By killing him and his son, his intentions are to fail the prophecy of Banquo’s children being the king and get rid of the suspicious Banquo.

the anecdote makes readers feel sorry for the man’s lack of heritage, then reminds readers that the man has an equally valuable heritage.