'Singleness' in the Bible
From Zebulun: 50,000 who could serve in the army, trained for battle with all kinds of weapons of war, with singleness of purpose to help David.
And they, continuing daily with one accord in the temple, and breaking bread from house to house, did eat their meat with gladness and singleness of heart,
He who exhorts (encourages), to his exhortation; he who contributes, let him do it in simplicity and liberality; he who gives aid and superintends, with zeal and singleness of mind; he who does acts of mercy, with genuine cheerfulness and joyful eagerness.
Servants, be obedient to them that are your masters according to the flesh, with fear and trembling, in singleness of your heart, as unto Christ;
Servants, obey in all things your masters according to the flesh; not with eyeservice, as menpleasers; but in singleness of heart, fearing God: