All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad is His slave and messenger.
We cannot verify whether or not this Deewaan (collection of poems) is authentically attributed to Ibn Hajar because this requires seeing the book and reading its introduction and seeing the copies/manuscripts that the editor relied upon, and other matters which prove whether this book can really be attributed to the author [Ibn Hajar].
In any case, what we can say is that making Tawassul by virtue of the Prophets and righteous people, meaning, asking Allaah by their persons, like saying, O Allaah I ask you by the high status of the Prophet or I call upon you by the right of such-and-such person, then there is a well-known difference of opinion among the scholars concerning it. Many of them are of the view that such a kind of Tawassul is permissible, but the preponderant opinion is that it is forbidden and not permissible.
Nonetheless, such an issue is a matter of Ijtihaad (personal reasoning) in which the difference of opinion is acceptable.
Ibn Taymiyyah said: "There is a justifiable difference of opinion with regard to the issue of supplicating Allaah by the virtue of the Prophets and righteous people without swearing by them..."
Shaykh Muhammad ibn Abdul Wahhaab said: "We do not object to those who do this [kind of Tawassul]. There is no objection to matters which are open to Ijtihaad. However, we object to that person who calls upon a creature more earnestly than he calls upon Allaah, intentionally goes to a grave and supplicates at the shrine of Shaykh ‘Abdul Qaadir [Al-Jeelaani] or any other person asking him to make for him a way out of his difficulties, to relieve his hardship, and fulfill his wishes. How can this person be equal to the one who only calls upon Allaah devoting his faith to Him and who does not call upon any other one than Allaah, but he says in his supplication: I ask you, O Allaah, by the virtue of your Prophet, or by the virtue of the Messengers, or by the virtue of righteous people, or purposefully goes to a grave of famous righteous person or whosoever so as to supplicate at that place, yet he does not call upon anybody else except Allaah devoting his faith to Him? So, how can they be equal?"
For more information, please refer to Fataawa 7775 and 89076.
Allaah Knows best.