He did that now and then but mostly to Engels, since it was clear his opinion was the one that mattered to Marx the most - and it was not even for money, you can see that when they first met in 1844 and basically immediately co-authored a book. Franz Mehring in his biography criticizes Marx for having pretty low tolerance level at which he cut the contacts, but looking at his huge correspondention i think Mehring is just salty for Marx dissing of Lasalle and Bakunin, in which Marx was correct and it happened only after long years of trying to cooperate (said Mehring book had more about Bakunin than about Engels ffs).