Meekness appears in the Beatitudes, in Psalm 37, and in the description of Moses in Numbers 12.
In Matthew 5:5:
5 Blessed are the meek: for they shall inherit the earth.
In Psalms 37:11:
11 But the meek shall inherit the earth; and shall delight themselves in the abundance of peace.
In Numbers 12:3:
3 (Now the man Moses was very meek, above all the men which were upon the face of the earth.)