Midrash sobre Ageu 1:15

(Exodus 19:1) "On the third month of the exodus of the children of Israel from the land of Egypt": We are hereby apprised that we number the months from the exodus from Egypt. This tells me only of months. Whence do I derive (the same for) years? From (Numbers 1:1) "in the second year of their exodus from Egypt." This tells me only of that period (i.e., the general period of the exodus.) Whence do I derive the same for succeeding periods? From (Ibid. 33:38) "in the fortieth year of the exodus of the children of Israel from the land of Egypt in the fifth month" (Av). All this, until they entered Eretz Yisrael. Whence do I derive the same for (the period) after they entered Eretz Yisrael? From (I Kings 6:1) "In the four hundred and eightieth year of the exodus of the children of Israel from the land of Egypt." All this, until the Temple was built. Once the Temple was built, they began to count from (the time of) its building, viz. (II Chronicles 8:1) "And it was, at the end of forty years of Solomon's building of the Temple of the L rd, etc." If they did not merit numbering from its building they numbered from its destruction, viz. (Ezekiel 40:1) "in the fourteenth year after the city was smitten." If they did not merit numbering for themselves, they numbered for others, viz. (Daniel 2:1) "And in the second year of the reign of Nevuchadnezzar, etc.", and (Chaggai 1:15) "In the second year of the reign of King Darius." And it is written (Song of Songs 1:8) "If you do not know, you fairest among the women, etc." and (Devarim 28:47-48) "Because you would not serve the L rd your G d … you will serve your foes, etc."