Musnad Abu Ya'la al-Mawsili 160:57

And with his chain of narration, he said: The Messenger of Allah (ﷺ) said: "Whoever prays the dawn prayer, he is under the protection of Allah, the Mighty and Majestic. So let not Allah pursue you for [violating] His protection. And whoever kills a person under a covenant who has the protection of Allah and the protection of His Messenger, he has violated the protection of Allah, the Mighty and Majestic. He shall not smell the fragrance of Paradise, even though its fragrance can be found from a distance of seventy autumns."