Where can I find the saying attributed to Hazrat 'Ali (R.A) that says not to force your children to behave like you for surely they have been created for a time which is different to your time?
Although this statement is popularly attributed to Imam 'Ali (A), as far as I know, there is no source clearly relating this source from Imam 'Ali (A).
However, if I recall correctly, it is attributed to him (without a chain of narration or the like) by Ibn Abi al-Hadid in Sharh Nahj al-Balaghah.
It is also attributed to Plato by some other classical Arab authors.
Allah knows best.