Whoever enters the state of consecration for Umrah and then decides to include Hajj along with it may do so, so long as he has not yet performed tawaf around the House or gone between Safa and Marwa. Ibn Umar did exactly this when he said, "If I am prevented from reaching the House, we will do as we did with the Messenger of Allah ﷺ."Then he turned to his companions and said, "Their affair is one and the same. I call you to witness that I have made Hajj binding upon myself along with the Umrah."
وحدثني عن مالك: أنه
من أهل بعمرة، ثم بدا له أن يهل بحج معها؛ فذلك له ما لم يطف بالبيت، وبين الصفا والمروة. وقد صنع ذلك ابن عمر حين قال: إن صددت عن البيت، صنعنا كما صنعنا مع رسول الله ﷺ. ثم التفت إلى أصحابه، فقال: ما أمرهما إلا واحد. أشهدكم: أني أوجبت الحج مع العمرة.