Hi, thanks for this subject
And added to your text
Al-Yaqeen -Certainty.
One who testifies should be certain about the meaning of the testification because if one doubts then the testimony will not benefit him. Allah says, “Only those are the believers who have believed in Allah and His Messenger, and afterward doubt not...” [Soorah al-Hujurat (49): 15]
So, if he doubts, then he is a hypocrite. Allah's Messenger said, “Whoever you meet behind this wall testifying 'La ilaha illAllah,' with certainty in his heart, then give him the glad tiding of Jannah.” [Saheeh al-Bukharee] Thus, he who does not have certainty in his heart does not deserve to enter Jannah.