What is the explanation of the apparent contradiction on manumission of slaves in ahadith?

There is [whole section in sahih bukhari](https://sunnah.com/bukhari/49) about manumitting slaves But there are other narrations like: > Jabir b. 'Abdullah said that a person among the Ansar declared his > slave free after his death, as he had no other property. This news > reached the Messenger of Allah (ﷺ) and he said: > > Who will buy him from me? And Nu'aim b. al-Nahham bought him for eight > hundred dirhams and he handed them over to him, 'Amr (one of the > narrators) said: I heard Jabir b. 'Abdullah as saying: He was a Coptic > slave, and he died in the first year (of the Caliphate of 'Abdullah b. > Zubair). > > https://sunnah.com/muslim/27/86 > Narrated Maimuna, the wife of the Prophet (ﷺ) that she manumitted her > slave-girl and the Prophet (ﷺ) said to her, "You would have got more > reward if you had given the slave-girl to one of your maternal > uncles." > > https://sunnah.com/bukhari/51/28 There was another hadith about 6 slaves being freed upon someones death and after that casting lots to decide who would be freed that was explained already so I excluded that. These narrations were put forward by some non-muslims.The narrations at first I found to be odd but then saw them in the Bukhari and Muslim so, can't really reject them. 2nd hadith apparently seems to say that giving slaves as gifts is more preferred than freeing them is that a correct veiw? How do I reconcile these two narrations with the narrations of manumitting slaves?