Fox and camel

The fox asked Shetri:

 How deep is this river?

 The camel replied:

 up to the knees

 But when the fox jumped into the river, the water passed over his head!

 As the fox was struggling in the water and drowning, he said to the camel:

 You said up to the knees!

 And the camel answered: Yes, up to my knee, not your knee!