Dhikr of Allah is the most excellent act of Allah's servants and is stressed over a hundred times in the Holy Qur'an. It is the most praiseworthy work to earn Allah's pleasure, the most effective weapon to overcome the enemy, and the most deserving of deeds in reward. It is the flag of Islam, the polish of hearts, the essence of the science of faith, the immunization against hypocrisy, the head of worship, and the key of all success.There are no restrictions on the modality, frequency, or timing of dhikr whatsoever. The restrictions on modality pertain to certain specific obligatory acts which are not the issue here, such as Salat. The Shari`a is clear and everyone knows what they have to do. Indeed, the Prophet said that the People of Paradise will only regret one thing: not having made enough dhikr in the world! Are not those who are making up reasons to discourage others from making dhikr afraid of Allah in this tremendous matter?
The Prophet said: "If your hearts were always in the state that they are in during dhikr, the angels would come to see you to the point that they would greet you in the middle of the road." Muslim narrated it. Imam Nawawi in his Sharh sahih muslim commented on this hadith saying: "This kind of sight is shown to someone who persists in meditation (muraqaba), reflection (fikr), and anticipation (iqbal) of the next world."