Ruling on smelling food and drink
Question

When we were young, our parents used to stop us if we try to smell foods or drinks. They used to say that smelling them is haram. A while ago I stopped a brother from smelling a food. He said to me, do not give me fatwa, provide an evidence if you have one. What is your answer to this?.
Praise be to Allah.In Islam, it is prohibited to breathe into the vessel and to blow into one’s drink. 
It was narrated from Abu Qataadah (may Allaah be pleased with him) that the Prophet (peace and blessings of Allaah be upon him) forbade breathing into the vessel. Narrated by al-Bukhaari (5630) and Muslim (267). 
What is meant is that it is forbidden to blow onto whatever is in the vessel of food or drink. 
Al-Shawkaani said in Nayl al-Awtaar (8/221): 
Vessel includes vessels for both food and drink. End quote. 
Al-Haafiz Ibn Hajar (may Allaah have mercy on him) said in Fath al-Baari (10/92): 
There are a number of ahaadeeth which forbid blowing into the vessel; it is also forbidden to breathe into the vessel, because that may result in some change due to the breathing, either because the breather’s mouth has a certain smell because of food for example, or because he has not used the miswak or rinsed his mouth for a long time, or because breathing brings out some vapours from the stomach. In all these cases blowing is even worse than merely breathing. End quote.  
Shaykh Ibn ‘Uthaymeen said in Sharh Riyadh al-Saaliheen (2/454): 
The wisdom behind that is that breathing into the vessel is off putting to the one who is going to drink from it after him. Some diseases from the stomach, lungs or mouth may be expelled with the breath and stick to the vessel, or he may choke if he breathes into the vessel. Hence the Prophet (peace and blessings of Allaah be upon him) forbade breathing into vessels; rather one should take three breaths, holding the vessel away from the mouth each time. End quote. 
It was narrated from Abu Sa’eed al-Khudri (may Allaah be pleased with him) that the Prophet (peace and blessings of Allaah be upon him) forbade blowing into one's drink. Narrated by al-Tirmidhi (1887) who said: a saheeh hasan hadeeth. It was also classed as saheeh by Ibn al-Qayyim in I’laam al-Muwaqqi’een (4/317). 
Shaykh Ibn ‘Uthaymeen (may Allaah have mercy on him) said in Sharh Riyadh al-Saaliheen (2/457): 
That is because if a person blows (into the vessel), some harmful things may come with the air that is exhaled, such as disease and the like. But some of the scholars made an exception in cases of necessity, such as if the drink is hot and he needs to drink it quickly. In that case some scholars granted a concession. But it is better not to blow on it, even if it is hot. If it is hot and he has another vessel, then he may pour some of it into that vessel then pour it back until it cools down. End quote. 
Once the reason for the prohibition on blowing or breathing into the vessel was understood, the scholars drew an analogy with everything that may lead to contamination of food and drink. 
Al-Shawkaani said in Nayl al-Awtaar (8/221): 
Just as one should not breathe into the vessel, one should not burp into it either. End quote.  
With regard to the ruling on smelling food or drink, if smelling the food or drink is done in such a way that the breath coming from the nose will come on the food then it is not allowed in this case. But if none of the breath will come on it, rather the person only wants to know what this food smells like so that he can know what it is, then there is nothing wrong with that. But when the mouth is brought too near to food or drink, that is usually accompanied by some of the breath that is exhaled from the nose. Hence some of the fuqaha’ regarded it as makrooh to smell food. 
It says in Radd al-Muhtaar, which is a Hanafi book (6/340): 
Food should not be eaten when it is hot, and it should not be smelled. End quote. 
It says something similar in Mughni al-Muhtaaj (4/412), which is a Shaafa’i book. 
But if a person wants to smell the steam coming from food from a distance, because of a need to do so and he is keen to ensure that none of his breath reaches the food or drink, then there is no reservation concerning that, in sha Allaah.. 
The Muslim should think about how keen Islam is to teach the Muslim all the etiquettes of living, even with regard to his food and drink. He should ponder how many of the books of our fuqaha’ (may Allaah have mercy on them) deal with etiquette and cleanliness, then let him see if there is any religion or line of thought which brought such sublime teachings as our religion did. Praise be to Allaah the Lord of the Worlds. 
And Allaah knows best.