Wherefore (dio). Probably this inferential conjunction (dia, o, because of which) goes with mh sklhrunhte (harden not) in verse Acts 8 rather than with blepete (take heed) in verse Acts 12 unless the long quotation be considered a parenthesis. The long quotation in verses Acts 7-11 is from Psalms 95:7-11 . After the quotation the author has "three movements" (Moffatt) in his discussion of the passage as applied to the Jewish Christians ( Psalms 3:12-19 ; Psalms 4:1-10 ; Psalms 4:11-13 ). The peril of apostasy as shown by the example of the Israelites is presented with vividness and power. As the Holy Ghost saith (kaqw legei to pneuma to agion). Just this phrase nowhere else in the N.T., except 21:11 (Agabus), though practically the same idea in 9:8 ; 10:15 . In 1 Timothy 4:1 the adjective "Holy" is wanting as in Revelation 2 ; Revelation 3 . But the writer quotes this Psalm as the Word of God and in Revelation 4:7 attributes it to David. If ye shall hear (ean akoushte). Condition of third class with ean and first aorist active subjunctive of akouw.