προσίετο. This verb is more often used by H. with a personal subject, e. g. 135. 1 ξεινικὰ νόμαια Πέρσαι προσίενται, but here of the thing, tr. ‘none took him’ (cf. our ‘I take it’ and ‘it takes me’). This second use is found in Aristoph., e. g. Eq. 359, Vesp. 741. Some see in the remark as to Amphiaraus (c. 49) a tradition inconsistent with the statement here. But the story—no doubt a Delphic one—is consistent; Apollo alone gave a complete answer, but the neighbouring shrine of Amphiaraus did well enough to save its credit.
προσεύχετο: he ‘worshipped’, recognizing in the oracle the power of the god. If the whole story is not simply a Delphic invention, we must suppose that Croesus was ‘working the oracle’ for the benefit of his Greek allies.
αὐτός is emphatic; Croesus carried out his own plan, so as to keep his secret to the last.