The Arabic expression بَعْضُكُمْ مِنْ بَعْضٍ (baʿḍukum min baʿḍin) is used twice in the Quran, in verses 3:195 and 4:25, and both times in the context of men and women.
3:195 Their Lord responded to them: “I never fail to reward any worker among you for any work you do, be you male or female— baʿḍukum min baʿḍin. Thus, those who immigrate, and get evicted from their homes, and are persecuted because of Me, and fight and get killed, I will surely remit their sins and admit them into gardens with flowing streams.” Such is the reward from GOD. GOD possesses the ultimate reward.
4:25 Those among you who cannot afford to marry free believing women, may marry believing slave women. GOD knows best about your belief, and baʿḍukum min baʿḍin, as far as belief is concerned. You shall obtain permission from their guardians before you marry them, and pay them their due dowry equitably. They shall maintain moral behavior, by not committing adultery, or having secret lovers. Once they are freed through marriage, if they commit adultery, their punishment shall be half of that for the free women. Marrying a slave shall be a last resort for those unable to wait. To be patient is better for you. GOD is Forgiver, Most Merciful.
So what is the meaning of this expression? The words بَعْضُكُمْ (baʿḍukum) and بَعْضٍ (baʿḍin) come from the same root which is ب ع ض which has the derivative meaning to distinct portions or people and is typically translated in the Quran as some, but when in conjunction together it means “to one another” as in comparing one group of people to another group of people. When the كُم (kum) is added to the suffix of a word, like in the word بَعْضُكُمْ (baʿḍukum), this signifies that the object or verb is in relation to plural form of you or your. These two words used in conjunction to each other occurs dozens of times in the Quran and the comparison will be dependent to how these two groups are being compared.
For example when the preposition عَلَىٰ (‘alaa) in the expression بَعْضَكُمْ عَلَىٰ بَعْضٍ (baʿḍukum ‘alaa baʿḍin)is used this means over such that it can be thought of as “one group over the other”
4:32 You shall not covet the qualities bestowed upon each other by GOD; the men enjoy certain qualities, and the women enjoy certain qualities. You may implore GOD to shower you with His grace. GOD is fully aware of all things.
Of in 6:65 we see the expression as بَعْضَكُم بَأْسَ بَعْضٍ (baʿḍukum basa baʿḍin) where basa means the wrath, evil, or tyranny. So this is indicating the wrath of one group to another.
6:65 Say, “He is certainly able to pour upon you retribution from above you, or from beneath your feet. Or He can divide you into factions and have you taste each others’ tyranny. Note how we explain the revelations, that they may understand.”
Another example is with the preposition of ل as in the expression بَعْضَكُمْ لِبَعْضٍ (baʿḍukum lebaʿḍin). The ل with a kasra, the diagonal stroke written below the consonant, when added to the prefix of a word signifies that this is a preposition “to, for, by”. So this expression would signify one group to another group and would be best translated as “you by each other.”
25:20 We did not send any messengers before you who did not eat food and walk in the markets. We thus test you by each other; will you steadfastly persevere? Your Lord is Seer.
So in the case of 3:195 and 4:25, how should we understand the word مِنْ min in the expression (baʿḍukum min baʿḍin) بَعْضُكُمْ مِنْ بَعْضٍ. The preposition min مِنْ typically is translated as “of, from, or among” and is typically used to signify that one person is part of another group that they are among them. So for take the example of 2:64
2:64 But you turned away thereafter, and if it were not for GOD’s grace towards you and His mercy, you would have been among the losers.
From this analysis we can translate the expression بَعْضُكُمْ مِنْ بَعْضٍ (baʿḍukum min baʿḍin) as “some of you [all] of some others” which would be a more literal translation as “you [all] are of one another” which indicates that these two groups are the same so therefore it should be better understood as “you all are the same as one another” or put another way “you all are equal to one another.”
3:195 Their Lord responded to them: “I never fail to reward any worker among you for any work you do, be you male or female— you are equal to another. Thus, those who immigrate, and get evicted from their homes, and are persecuted because of Me, and fight and get killed, I will surely remit their sins and admit them into gardens with flowing streams.” Such is the reward from GOD. GOD possesses the ultimate reward.
4:25 Those among you who cannot afford to marry free believing women, may marry believing slave women. GOD knows best about your belief, and you are equal to one another, as far as belief is concerned. You shall obtain permission from their guardians before you marry them, and pay them their due dowry equitably. They shall maintain moral behavior, by not committing adultery, or having secret lovers. Once they are freed through marriage, if they commit adultery, their punishment shall be half of that for the free women. Marrying a slave shall be a last resort for those unable to wait. To be patient is better for you. GOD is Forgiver, Most Merciful.
It is worth noting that in regards to 4:25 the despite the expression “as far as belief is concerned” is not explicitly stated in the Arabic, it is implied because the context of the expression is regarding the faith of the individuals being compared.