In the name of Allah, the All-Merciful, the Mercy-Giving

All praise is due to Allah. Peace and blessings be upon Prophet Muhammad.

 

Laylat al-Qadr occurs in the last ten nights of Ramadan; particularly in the odd numbered ones. There is a great difference of opinion among scholars concerning the exact night it occurs in.

 

Hiding the exact date of that night refers to the unfathomable divine wisdom. `Ubadah ibn al-Samit reported “The Prophet (peace and blessings be upon him) came out to inform us about the Night of Qadr but two Muslims were quarreling with each other. So, the Prophet (peace and blessings be upon him) said, “I came out to inform you about the Night of Qadr but such-and-such persons were quarreling, so the news about it had been taken away (i.e. I forgot it); yet that might be for your own good …”
Therefore, it is recommendable to increase worship in all the last ten nights of Ramadan; particularly in the odd numbered ones.

Allah Almighty knows best.