Because you have been commanded to follow him. Allah Almighty says: «‏‏‏‏أُولَـٰئِكَ الَّذِينَ هَدَى اللَّـهُ ۖ فَبِهُدَاهُمُ اقْتَدِهْ ۗ» ‏‏‏‏ [ سورۃ الانعام:90 ] "These are the ones whom Allah has guided, so

Ibn Abi Mulaikah (may Allah have mercy on him) narrates that a man from the Quraysh requested Abdullah bin Umar (may Allah be pleased with them both), saying: "I am with my family and camels carrying our belongings, and our goods are on these weak donkeys. May I depart from Muzdalifah at night?" He replied: "Ibrahim (peace be upon him) spent the night in Mina, and when morning came and the sun rose, he set out towards the plain of Arafat, until he reached his place in Arafat and settled there." In the narration of Mu’ammal, it is stated: "He settled at his place in Arafat." Then, after the sun had passed its zenith, he stood in Arafat (making supplications). When the sun set, he came to Muzdalifah and settled at his place. Then he spent the night in Muzdalifah. If he prayed the morning prayer early (in darkness), he would stay (and make supplications); if he performed the Fajr prayer after the morning became bright, he would set out for Mina. This is the blessed way of your forefather Ibrahim (peace be upon him), and Allah Almighty has commanded your Prophet to follow him. This is the hadith of Ibn ‘Ulayyah.