Answered by Shaykh Abdurrahman ibn Yusuf Mangera
What are the six kalimas?
Actually, these kalimas were compiled together for children to memorize and learn the basic fundamentals of a Muslim’s beliefs. They are not found altogether in any one hadith or narration from the Prophet (peace be upon him). However, some of them can be found individually in the narrations. To see the virtues of some of these kalimas one can read the Chapter of Dhikr in the Fada’il A’mal of Shaykh Zakariya Khandelwi.
Children are told that memorizing these kalimas will come in use in the grave. This is to encourage them to learn them quickly. Yes, if someone is to act on the dictates of these kalimas after memorizing them, then surely they will come in use in the grave.
And Allah knows best.
Abdurrahman ibn Yusuf