I asked Ibn Umar about the prayer at Mina.He said, "Have you heard of Muhammad ﷺ?"I replied, "Yes, and I believe in him."He said, "He used to pray two rakahs at Mina."
حدثنا وكيع حدثنا سعيد بن السائب
سألت ابن عمر عن الصلاة بمني قال هل سمعت بمحمد ﷺ قلت نعم وآمنت به قال فإنه كان يصلي بمني ركعتين
Its isnad is sahih, and it is a repetition of 4760 with this same isnad. See also 5214.