Arcana Coelestia #7446
7446. 'And tomorrow will this sign be' means the manifestation of Divine power thereby for evermore. This is clear from the meaning of 'tomorrow' as for evermore, dealt with in 3998; and from the meaning of 'a sign' as a corroboration of the truth, and consequent knowledge of it, dealt with in 6870, and therefore the manifestation of Divine power. For in former times truth, and at the same time Divine power were made manifest by means of signs.
Arcana Coelestia #3998
3998. 'On the morrow' means into eternity. This is clear from the meaning of 'the morrow'. When yesterday, today, or tomorrow is mentioned in the Word eternity is meant in the highest sense, 'yesterday' meaning from eternity, 'today' eternity, and 'tomorrow' into eternity. As regards 'today' meaning eternity, see 2838. Indeed periods of time mentioned in the Word - ages, years, months, weeks, days, hours - mean states, as has often been shown. With the Lord however there are no states, but everything is eternal and infinite. From this it is evident that 'on the morrow' means into eternity.