Luke 8:13

‘And those on the rock are they who, when they have heard, receive the word with joy, and these have no root, who for a while believe, and in time of temptation fall away.'

Those on the rock were people whose hearts were like rock, totally impenetrable, but with a veneer of interest on top. When the seed fell on them they received it with apparent joy, for they found it pleasant to the ear. But the seed obtained no root, for they did not want their lives to be over-affected, and while they ‘believed it' for a while, when times of testing came they fell away. For similar belief compare John 2:23). They did not see it as worth suffering for. It is a reminder to us that we need to ‘sow deep'.