As for the condition that Islam stipulated for polygamy, it is the Muslim’s confidence in himself to be fair between his two wives or his wives in food, drink, clothing, housing, overnight stays, and spending on each. Whoever is not confident in himself in being able to fulfil these rights with justice and equality, it is forbidden for him to marry more than one wife. Allah SWA says: But if you fear that you cannot do justice, then one only. Al Nisa: 3. The Prophet ﷺ said: “Whoever has two wives and is inclined to favor one of them over the other, he will come on the Day of Resurrection with half of his body leaning”
The inclining to favor one of the wives that the hadith has warned us of is the unfairness to her in her rights. This does not mean unfairness of the heart, because this is one of things which he cannot control, and which Allah has pardoned and forgiven him for. Allah SWA says: (You will never be able to maintain ˹emotional˺ justice between your wives—no matter how keen you are. So do not totally incline towards one leaving the other in suspense. And if you do what is right and are mindful ˹of Allah˺, surely Allah is All-Forgiving, Most Merciful). Al Nisa: 129.
For this reason, the Prophet ﷺ used to divide and be just, and he said: (O God, this is my division concerning what I possess, so do not blame me concerning what You possess and I do not). It means what he does not have control over such as the matters of the heart, and emotional tendency to one of them specifically. And if he wanted to travel he would judge between them by taking lots, so whoever’s arrow was removed he would travel with her, and he did this to remove any envy and to satisfy all.