I prayed Maghrib with him as three units and Isha as two units with a single iqamah. Malik bin Khalid al-Harithi said to him, "What kind of prayer is this, Abu Abdul-Rahman?"He replied, "I prayed it this way with the Messenger of Allah ﷺ in this very place, with a single iqamah."
حدثنا عبد الرزاق أخبرنا سفيان عن أبي إسحاق عن عبد الله بن مالك
صليت معه المغرب ثلاثا والعشاء ركعتين بإقامة واحدة فقال له مالك بن خالد الحارثي ما هذه الصلاة يا أبا عبد الرحمن قال صليتها مع رسول الله ﷺ في هذا المكان بإقامة واحدة
Its isnad is sahih. It is a repetition of 4676 with similar wording, and we have already discussed it in detail at 4452. Abu Dawud also narrated it, 1:136, with wording similar to this, and in it the one who asked Ibn Umar was Malik bin Harith, whereas in what preceded at 4676 the narration has it as Abdullah bin Malik, that is, Abdullah bin Malik bin Harith, while here it is Malik bin Khalid Harithi.If the questioner was Malik bin Harith, it is quite likely that he was Malik bin Harith Hamdani, whose kunya was Abu Musa. He has a biography in Tahdhib, and Ibn Hibban mentioned him among the trustworthy narrators, and Bukhari gave his biography in Kabir 4/1/307, saying that he heard from Ali, and that Muhammad bin Qays narrated from him.But if, as it appears here, he was Malik bin Khalid Harithi, then I do not know who he is, and I have found no biography of him in the references available to me. In any case, the hadith is sahih. The disagreement over who the questioner was does not affect this, for in a gathering like that of Ibn Umar it would not be unusual for two or three questioners to come forward one after another, with him answering each in turn.