Concerning the āyah in Sūrah al-Fātiḥah:

اهْدِنَا الصِّرَاطَ الْمُسْتَقِيمَ ‎﴿٦﴾‏

Guide us to the straight path (of beneficial knowledge coupled with righteous action).
[al-Fātiḥah, 1:6]

Al-Imām Ibn al-Qayyim (d. 751 AH) commented :
“It refers to two individual forms of guidance, true success cannot occur without them both. The first is to gain both general and detailed knowledge of the truth we were formerly ignorant of in order to allow that truth to inspire us and make us want to follow it, inwardly and outwardly. The second form of guidance is the creation of the willpower required to act in accordance with that guidance as manifested in our speech, actions, and determination. Finally, it refers to keeping us steadfast on this path and stabilising us on it until death.

From this, we can acknowledge the dire need for the servant (of Allāh) to make this supplication, above all other needs.

We also ascertain that it is incorrect to say: “If we are already guided [to Islām], why should we ask for guidance?” In reality, the aspects of the truth we remain ignorant of exponentially outweigh what we know. And the actions we choose to leave off, whether it be out of laziness or devaluing [of those actions], may be equal [in reward] to the actions we engage in. Those actions may also be greater or lesser [in reward]. The same can be said about the actions we wish to engage in but lack the ability to do. For the [aspects of the truth] that we know in general but lack detailed knowledge of, are beyond enumeration. Thus, we are in dire need of complete guidance. As for the one who can perfect this matter [ gaining knowledge and acting according to it], then his supplication for guidance is to keep him steadfast and stable [on the straight path].”

Source: Madārij al-Sālikīn 1:26-27
Translated by: Riyāḍ al-Kanadī