Although the Witches wanted to meet Macbeth 'upon the heath', Banquo, accompanying Macbeth, chanced to see them first. Banquo was puzzled at their 'wither'd' looks and 'wild' attire; he doubted if they were 'the inhabitants o' the earth'; he alluded to their wizened appearance and their female sexual identity being contradicted by their 'beards'. As Macbeth asked them to speak, the three Witches made their proclamations.Banquo noticed Macbeth's immediate reaction--'..why do you start, and seem to fear/Things that do sound so fair?' He could also see Macbeth 'rapt withal'. Since the Witches welcomed Macbeth with 'present grace and great prediction/Of noble having and of royal hope', Banquo demanded his share of 'supernatural soliciting'. The Witches then greeted Banquo with prophecies, but in a language of paradox--'Lesser than Macbeth, and greater', 'Not so happy, yet much happier' & 'Thou shalt get kings, though be none'. Macbeth then charged the Witches for more, but they vanished into the air.
What followed in this scene--act1 sc.3--revealed the difference between Macbeth and Banquo in their attitudes to the Witches and their prophecies. While Macbeth took the Witches' predictions very seriously, especially that of kingship of Scotland, Banquo showed his scepticism and indifference. While Macbeth was so keen to have more, Banquo was incredulous of what he had just heard. Banquo advised Macbeth to be on guard against such uncalled-for well-wishing:'And oftentimes, to win us to our harm,/The instruments of darkness tell us truths,/Win us with honest trfles...'. The immediate fulfilment of one of the predictions effects a change in both, but still Banquo differs from Macbeth, and expresses his suspicion--'What! can the devil speak true?' However, it is not correct to say that Banquo was fully immune to temptation, for these lines suggest how Banquo fought within himself to smother his unscrupulous thoughts--'Merciful powers,/ Restrain in me the cursed thoughts that nature / Gives way in repose'.