It could not have been a dream from Shaitan because Abraham عليه السلام was a prophet. The dreams of prophets are true and are a form of revelation. Revelation is protected from Shaitan. Abraham knew this and that is why he didn't ignore it. Similarly Ishmael\Isaac عليه السلام knew this and this is why he called it a command from Allah and told his father to obey it.
أول ما بدئ به رسول الله صلى الله علي وسلم من الوحي، الرؤيا الصادقة في النوم، فكان لا يرى رؤيا إلا جاءت مثل فلق الصبح
The commencement of the Divine Inspiration to Allah's Messenger (ﷺ) was in the form of good righteous (true) dreams in his sleep. He never had a dream but that it came true like bright day light.
ورؤيا الأنبياء وحي، فإنها معصومة من الشيطان، وهذا باتفاق الأمة
The dreams of the Prophets are revelation, as they are protected from the devil, the Ummah is agreed upon this.
— Madarij as-Saalikin