It is narrated from Muhammad bin Sirin that Sayyiduna Ibn Abbas (may Allah be pleased with them both) said concerning this verse: "And upon those who are able to fast is a ransom: the feeding of a poor person" [Surah al-Baqarah: 184] - "Then the other verse abrogated it": "So whoever of you witnesses the month, let him fast it" [Surah al-Baqarah: 185].
Hadith Referenceالمعجم الكبير للطبراني / باب العين / 12819