More a curiosity than a contradiction:
... And if you see any mortal, say: Surely I have vowed a fast to the Beneficient, so I shall not speak to any man today. -- Sura 19:26
Is that similar to eat samples of food in order to demonstrate all the things that you are not allowed to eat during fasting?
Answer: How difficult to the best woman in the universe to say one time that she will not talk for certain amount of time.
19:26 "So eat and drink and cool (thine) eye. And if thou dost see any man, say, 'I have vowed a fast to ((Allah)) Most Gracious, and this day will I enter into not talk with any human being'"
فَكُلِي وَاشْرَبِي وَقَرِّي عَيْنًا فَإِمَّا تَرَيِنَّ مِنَ الْبَشَرِ أَحَدًا فَقُولِي إِنِّي نَذَرْتُ لِلرَّحْمَنِ صَوْمًا فَلَنْ أُكَلِّمَ الْيَوْمَ إِنسِيًّا