'Hard' in the Bible

'And he also who hath received the one talent having come, said, Sir, I knew thee, that thou art a hard man, reaping where thou didst not sow, and gathering from whence thou didst not scatter;

for they understood not concerning the loaves, for their heart hath been hard.

And the disciples were astonished at his words, and Jesus again answering saith to them, 'Children, how hard is it to those trusting on the riches to enter into the reign of God!

many, therefore, of his disciples having heard, said, 'This word is hard; who is able to hear it?'

And he said, 'Who art thou, Lord?' and the Lord said, 'I am Jesus whom thou dost persecute; hard for thee at the pricks to kick;'

and we all having fallen to the earth, I heard a voice speaking unto me, and saying in the Hebrew dialect, Saul, Saul, why me dost thou persecute? hard for thee against pricks to kick!

concerning whom we have much discourse and of hard explanation to say, since ye have become dull of hearing,

as also in all the epistles, speaking in them concerning these things, among which things are certain hard to be understood, which the untaught and unstable do wrest, as also the other Writings, unto their own destruction.