What is the significance of omitting the preposition "li" (ل) from the Almighty’s saying: "Those who responded to Allah and the Messenger after they had been wounded"?

Some scholars have mentioned that the wisdom behind the omission of the preposition in the verse, "Those who responded to Allah and the Messenger after the wound had afflicted them," is that the 'responding' here refers specifically to obeying a particular command, which was joining the Quraysh army in Hamra' al-Asad. This differs from the verse, "to Allah and to the Messenger," which indicates a more general response.