The lam is for the confirmation of the negation. Its meaning is that the departure of all people from their homelands to seek knowledge is not correct nor possible. [Mahamud said: "Its meaning is that the departure of all people to seek knowledge is not possible... etc." Ahmad said: His saying وَما كانَ الْمُؤْمِنُونَ لِيَنْفِرُوا كَافَّةً in the first interpretation: is a command, not a prohibition. In the second: it is a statement and the intended meaning is prohibition, because in the first it refers to the departure of the people of the desert to the city for understanding, and if it were possible for all to do it, it would be permissible or obligatory. If it were not possible, it would be obligatory for some of them to act on behalf of the others in the manner of the obligation of sufficiency. As for the second, it is because the believers departed from the city for jihad all together, and that was possible and indeed occurred. They were prohibited from neglecting understanding altogether and were commanded to pursue it as an obligation of sufficiency, and Allah knows best. Ahmad said: I find no excuse for my delay in attending the battles except for directing my intention to warn this author. I have indeed understood the fundamentals of religion and the principles of beliefs, supported by the verses of the Noble Book, along with what it contains of safeguarding its domain from the plots of the people of innovation and desires. With that, I hope from Allah good guidance. May Allah grant us goodness, guide us to what pleases Him, and make our deeds sincere for His noble face.