Allah's statement,

﴿فَإِنْ خِفْتُمْ أَلاَّ تَعْدِلُواْ فَوَحِدَةً أَوْ مَا مَلَكَتْ أَيْمَـنُكُمْ﴾

(But if you fear that you will not be able to deal justly (with them), then only one or what your right hands possess.) The Ayah commands, if you fear that you will not be able to do justice between your wives by marrying more than one, then marry only one wife, or satisfy yourself with only female captives, for it is not obligatory to treat them equally, rather it is recommended. So if one does so, that is good, and if not, there is no harm on him. In another Ayah, Allah said,

﴿وَلَن تَسْتَطِيعُواْ أَن تَعْدِلُواْ بَيْنَ النِّسَآءِ وَلَوْ حَرَصْتُمْ﴾

(You will never be able to do perfect justice between wives even if it is your ardent desire) ﴿4:129﴾. Allah said,

﴿ذلِكَ أَدْنَى أَلاَّ تَعُولُواْ﴾

(That is nearer to prevent you from Ta`ulu), meaning, from doing injustice. Ibn Abi Hatim, Ibn Marduwyah and Abu Hatim Ibn Hibban, in his Sahih, recorded that `A'ishah said that, the Prophet said that the Ayah,

﴿ذلِكَ أَدْنَى أَلاَّ تَعُولُواْ﴾

(That is nearer to prevent you from Ta`ulu), means, from doing injustice. However, Ibn Abi Hatim said that his father said that this Hadith to the Prophet is a mistake, for it should be attributed to `A'ishah not the Prophet . Ibn Abi Hatim reported from Ibn `Abbas, `A'ishah, Mujahid, `Ikrimah, Al-Hasan, Abu Malik, Abu Razin, An-Nakha`i, Ash-Sha`bi, Ad-Dahhak, `Ata' Al-Khurasani, Qatadah, As-Suddi and Muqatil bin Hayyan that Ta`ulu means to deviate ﴿from justice)