Tell us about our marching to fight the people of Sham! Is it by the fate of Allah?’

Imam al-Hadi (a.s.) narrated from his fathers that a man from Iraq asked Imam Ali (a.s.) when he was marching (with his army) for the battle of Siffeen, ‘Tell us about our marching to fight the people of Sham! Is it by the fate of Allah?’
Imam Ali (a.s.) said, ‘O sheikh (old man), yes, it is. By Allah, you do not mount a castle or descend into a valley unless it has been determined by the fate of Allah.’
The man said, ‘I expect the reward of my efforts from Allah O Ameerul Mo'minin.’
Imam Ali (a.s.) explained fate by saying, ‘O sheikh, wait! You may think it is inevitable fate and inescapable doom! If it is so, then reward and punishment, enjoining and forbidding, scolding, warning and threatening will be void, and a bad doer will not to be blamed and a good doer will not be rewarded. A good doer will be worthier of being blamed than a guilty one, and a guilty one will be worthier of reward than a good doer. This opinion is of idolaters, enemies of Allah, fatalists, and the magi. O sheikh, Allah the Almighty has charged His people but has given them the option to do or not to do, and forbidden them as warning. He gives much for a little. He is not disobeyed out of defeat and He is not obeyed by force. He has not created the heavens, the earth, and what is between them in vain. That is the opinion of those who disbelieve, and woe unto those who disbelieve from the Fire…’
The man got up reciting some verses of poetry in which he praised Imam Ali (a.s.) and showed his satisfaction to what Imam Ali said ( At-Tawhid, p.380-381)