The story is told that when Luqmaan's (A.S.) Master bought him, the other slaves looked upon him as being despicable. One day the Master sent all of them into the garden to pick fruit. All the slaves started eating the fruit. They ate to their heart's delight and went to inform the Master that Hazrat Luqmaan (A.S.) had eaten the fruit. This made the Master very much displeased with Luqmaan (A.S.).
Hazrat Luqmaan (A.S.) advised the Master: "Please investigate this matter thoroughly. I did not eat the fruit. I will tell you of a plan which will prove who the culprits were. The whole truth will become clear to you. Make preparations for hunting".
From the stable the Master ordered that horses be brought. The Master sat down on his horse. Then Hazrat Luqmaan (A.5.) said: "Proceed speedily in the direction of the desert. But before you proceed give everyone of the slaves, warm water to drink. Let everyone drink himself to the full with warm water. Very soon you will discover who the real culprits are".
The result was that when those who had eaten the fruit were forced to run along, the quick movements caused them to start vomiting. That was because after drinking hot water, the fast movements caused their stomachs to become even more heated. Moreover the path they trod which led to the desert was an uneven one, with ups and downs. This made vomiting unavoidable. In the vomit, the signs of their having eaten the fruit was quite clear, because the time which passed since they had eaten was too short for the fruit to be digested. Hazrat Luqmaan (A.S.) did not vomit as there was no fruit in his stomach.
Through the wise plan of Hazrat Luqmaan (A.S.) all the slaves were put to shame and were embarrassed. The Master became very pleased with the wisdom of the plan and as a result
Luqmaan (A.S.) became a favourite of the Master. Maulana Rumi (R.A.) says:
"When such is the wisdom of Luqmaan (AS.), Imagine the wisdom of the True Master of all".
source: Maulana Yunus Patel