Ge-costian

According to the Old English Dictionary:

-costnian;

ge-costian

p. ode; pp. od. [costian to tempt] To tempt, try, prove; tentāre, probāre :-- He gecostaþ wildeóra worn it tryeth the multitude of beasts, Salm. Kmbl. 610; Sal. 304. Ne eart ðú clǽne gecostad thou art not thoroughly proved, Exon. 41 a; Th. 136, 36; Gú. 552 : 40 b; Th. 134, 13; Gú. 507. [O. Sax. gi-kostón : O. H. Ger. gi-costót proved, tried.] ge-costian