The Prophet (peace and blessings be upon him) said: "By Allah! The world and whatever is in it (its destruction) is easier in the sight of Allah than unjustly killing a believer."
Yazid bin Ziyad, also called Ibn Abi Ziyad al-Shami, is munkar al-hadith (his narrations are rejected); and the first text has been narrated through another chain from al-Zuhri as mursal.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الجنايات / 15867