Ruling on using someone else’s belongings without asking him for permission, when you know that he would agree to that
Question

What is the ruling on not asking for permission when using people’s belongings, when we know that they would agree to that?
Praise be to Allah.The basic principle is that it is forbidden to make use of someone else’s property except with his willing consent, because the Prophet (blessings and peace of Allah be upon him) said: “It is not permissible [to take or use] the property of any individual except with his willing consent.” Narrated by Ahmad (20172); classed as saheeh by al-Albaani in Saheeh al-Jaami‘ (7662).
Abu Dawood (5003) narrated from ‘Abdullah ibn as-Saa’ib ibn Yazeed, from his father, from his grandfather, that he heard the Messenger of Allah (blessings and peace of Allah be upon him) say: “No one of you should take his brother’s property in play or in earnest. And whoever has taken his brother’s staff, let him return it.” Classed as hasan by al-Albaani in Saheeh Abi Dawood.
Ahmad (27803) narrated from Abu Humayd as-Saa‘idi that the Prophet (blessings and peace of Allah be upon him) said: “It is not permissible for a man to take his brother’s staff without his willing consent.” That is because the Messenger of Allah (blessings and peace of Allah be upon him) emphatically forbade the property of one Muslim to another Muslim. Classed as saheeh by al-Albaani in as-Silsilah as-Saheehah (5/280).
As-San‘aani said in Subul as-Salaam (3/61): The hadiths indicate that it is prohibited to take a Muslim’s property, even a small amount, except with his willing consent, and there is scholarly consensus on that.
End quote.
If it is known that the person agrees to let others use his things, then there is nothing wrong with it in that case, because of the hadiths quoted above and because Allah, may He be exalted, says (interpretation of the meaning):
{There is not upon the blind [any] constraint nor upon the lame constraint nor upon the ill constraint nor upon yourselves when you eat from your [own] houses or the houses of your fathers or the houses of your mothers or the houses of your brothers or the houses of your sisters or the houses of your father's brothers or the houses of your father's sisters or the houses of your mother's brothers or the houses of your mother's sisters or [from houses] whose keys you possess or [from the house] of your friend. There is no blame upon you whether you eat together or separately. But when you enter houses, give greetings of peace upon each other - a greeting from Allah, blessed and good. Thus does Allah make clear to you the verses [of ordinance] that you may understand} [an-Noor 24:61].
Al-Qurtubi (may Allah have mercy on him) said in his Tafseer (12/315): With regard to the words {or [from the house] of your friend} … the friend is the one who is sincere to you in his friendship, and you are sincere to him in his friendship.
However, it was said that this verse was abrogated by the verses {do not enter the houses of the Prophet except when you are permitted} [al-Ahzaab 33:53] and {And if you do not find anyone therein, do not enter them} [an-Noor 24:28], and by the words of the Prophet (blessings and peace of Allah be upon him): “It is not permissible [to take or use] the property of any Muslim except with his willing consent.”
It was said: This is clear, and the ruling based on it is more correct. Muhammad ibn Thawr quoted Ma‘mar as saying: I entered the house of Qataadah and saw some fresh dates there, so I started to eat them. He said: What is this? I said: I saw some fresh dates in your house, so I ate. He said: You did well. Allah, may He be exalted, says: {or [from the house] of your friend}. ‘Abd ar-Razzaak narrated from Ma‘mar that Qataadah said concerning the verse {or [from the house] of your friend}: If you enter the house of your friend without asking him for permission, there is nothing wrong with that.
Ma‘mar said: I said to Qataadah: May I drink from this vessel? He said: You are my friend! What is this asking permission?
The Prophet (blessings and peace of Allah be upon him) used to enter a garden of Abu Talhah that was called Bayraha’ and drink from a fresh water source there without his permission, as our scholars stated. And they said that water belongs to its owners, and if it is permissible to drink from the water of a friend without his permission, then it is permissible to eat his fruit and food if it is known that the owner would agree to that, because that is of no great significance and is readily available, or because of the friendship between them.
Similarly, Umm Haraam fed the Prophet (blessings and peace of Allah be upon him) when he slept in her house, because usually whatever food is in the house belongs to the man and his wife is not the owner of that food.
All of this applies so long as you do not take food away with you, and do not intend thereby to save your own money, and so long as what is taken is only a small amount. End quote.
As-Sa‘di (may Allah have mercy on him) said in his Tafseer (p. 575): This passage points to the general holistic principle that “custom and tradition make exceptions to what is stated in general, just as one statement may make exempt what is stated in general.” Because in principle it is not allowed to eat the food of another person, Allah made an exception allowing one to eat from the houses of the people mentioned here, because custom and tradition allow that. With regard to issues that depend on permission from the owner of the thing, if it is known that he gave permission, either verbally or according to custom, it is permissible to go ahead and make use of it.
Based on that, if you know that these people agree to you using their things, there is nothing wrong with using them without asking them for permission, because permission has been given according to custom.
And Allah knows best.