You say that a man cannot obtain provision simply through supplication, but in Soorat Aal ‘Imran, Allah tells us that He used to give Maryam provision without any effort on her part, so how do you explain that?
The basic principle regarding provision (rizq) and other matters is based on means and taking measures, so provision cannot be obtained except through effort, as Allah, may He be exalted, says (interpretation of the meaning):
“It is He who made the earth tame for you - so walk among its slopes and eat of His provision - and to Him is the resurrection”
[al-Mulk 67:15].
Ibn Katheer (may Allah have mercy on him) said in his Tafseer (8/180):
Ibn ‘Abbaas, Mujaahid, Qataadah, and as-Saddi said: “Its slopes” means its different regions, mountain paths and areas.
Ibn ‘Abbaas and Qataadah said: “its slopes” means its mountains. End quote.
Ahmad (370), at-Tirmidhi (2344) and Ibn Maajah (4146) narrated that ‘Umar ibn al-Khattaab said: The Messenger of Allah (blessings and peace of Allah be upon him) said: “If you were to put your trust in Allah as you should, you would be given provision like the birds: they go out hungry in the morning and come back with full bellies in the evening.”
Classed as saheeh by al-Albaani and Shu‘ayb al-Arna’oot.
The hadith clearly states that the birds go out in the morning, at the beginning of the day, looking for food. This refers to making effort and taking measure to seek provision, even though the hadith affirms the importance of putting one’s trust in Allah [tawakkul] and explaining the right way to do so. Thus it indicates that taking appropriate measures and means is not contrary to putting one’s trust in Allah; rather it is part of perfecting that trust in Him.
This is the general principle that Allah has prescribed for His slaves, that they should seek their objectives by taking measures through putting their trust in Allah and making efforts. However, Allah may bring about something extraordinary, and grant provision to one of His slaves without any measures or effort on the part of that person, as a miracle for a Prophet or by way of honouring (karaamah) one of His close friends. This is what happened to Maryam (peace be upon her); Allah granted her provision without any apparent physical measures, by way of honouring her, because she was not a prophetess, according to the majority of scholars.
Allah, may He be exalted, says (interpretation of the meaning):
“So her Lord accepted her with good acceptance and caused her to grow in a good manner and put her in the care of Zechariah. Every time Zechariah entered upon her in the prayer chamber, he found with her provision. He said, ‘O Mary, from where is this [coming] to you?’ She said, ‘It is from Allah. Indeed, Allah provides for whom He wills without account.’
At that, Zechariah called upon his Lord, saying, ‘My Lord, grant me from Yourself a good offspring. Indeed, You are the Hearer of supplication’”
[al ‘Imraan 3:37-38].
Al-Qurtubi (may Allah have mercy on him) said:
When Zakariyya entered upon her, he would find winter fruits with her in the summer, and summer fruits with her in the winter.
He said: O Maryam, from where is this coming to you?
She said: It is from Allah.
At that point, Zakariyya began to hope for a son and said: The One Who gives her this is able to bless me with a son. End quote.
Al-Baghawi (may Allah have mercy on him) said in his Tafseer (2/32):
The narrators said: When Zakariyya saw that, he said: The One Who is able to provide Maryam with fruit out of season, with no means, is indeed able to rectify my wife’s condition and bless me with a son when I am old, and he began to hope for a son. End quote.
Ibn Katheer (may Allah have mercy on him) said in his Tafseer (2/36):
“He found with her provision”. Mujaahid, ‘Ikrimah, Sa‘eed ibn Jubayr, Abu’ash-Sha‘thaa’, Ibraaheem an-Nakha‘i, ad-Dahhaak, Qataadah, ar-Rabee‘ ibn Anas, ‘Atiyyah al-‘Awfi, as-Saddi and ash-Sha‘bi said: It means that he found summer fruit with her in the winter, and winter fruit with her in the summer.
It was narrated from Mujaahid: “He found with her provision” means: knowledge, or pages containing knowledge. This was narrated by Ibn Abi Haatim. The former is more correct, and this is proof for the honours (karaamaat) bestowed upon the close friends (awliya’) of Allah. And there are many similar reports in the Sunnah. End quote.
Conclusion:
The basic principle is that provision does not come except through effort, unless it is a miracle, such as the sending down of the table spread to ‘Eesaa (peace be upon him), or the increase of food and water for the Messenger of Allah (blessings and peace of Allah be upon him) or the honour (karaamah) that was bestowed upon Maryam.
That may be in answer to a supplication (du`a) offered by the individual, so he is granted provision through the blessing (barakah) of his du`a; du`a is also one of the means prescribed in Islamic teachings. But it is not permissible for anyone to neglect to take appropriate measures to attain what he seeks in either spiritual or worldly terms, relying only on du`a, because that is akin to conceit.
And Allah knows best.