Allah tells us how the disbelievers mocked the Messenger when they saw him. This is like the Ayah,

[وَإِذَا رَآكَ الَّذِينَ كَفَرُواْ إِن يَتَّخِذُونَكَ إِلاَّ هُزُواً]

(And when the disbelievers see you, they take you not except for mockery) (21:36), which means that they tried to find faults and shortcomings in him. Here Allah says:

[وَإِذَا رَأَوْكَ إِن يَتَّخِذُونَكَ إِلاَّ هُزُواً أَهَـذَا الَّذِى بَعَثَ اللَّهُ رَسُولاً ]

(And when they see you, they treat you only in mockery (saying): "Is this the one whom Allah has sent as a Messenger'') i.e., they said this by way of belittling and trying to undermine him, so Allah put them in their place, and said:

[وَلَقَدِ اسْتُهْزِىءَ بِرُسُلٍ مِّن قَبْلِكَ]

(And indeed Messengers before you were mocked at) (6:10)

[إِن كَادَ لَيُضِلُّنَا عَنْ ءَالِهَتِنَا]

(He would have nearly misled us from our gods,) They meant: `he nearly turned us away from worshipping idols, and he would have done so, had we not been patient and persevered in our ways.' So Allah said, warning and threatening them:

[وَسَوْفَ يَعْلَمُونَ حِينَ يَرَوْنَ الْعَذَابَ]

(And they will know, when they see the torment...)