user23662: 
Take another case of a mendicant who lives close by a jungle thicket. As they do so, their mindfulness becomes established, their mind becomes immersed in samādhi, their defilements come to an end, and they arrive at the supreme sanctuary. But the necessities of life that a renunciate requires—robes, almsfood, lodgings, and medicines and supplies for the sick—are hard to come by. That mendicant should reflect:
‘While living close by this jungle thicket, my mindfulness becomes established … But the necessities of life are hard to come by. But I didn’t go forth from the lay life to homelessness for the sake of a robe, almsfood, lodgings, or medicines and supplies for the sick. Moreover, while living close by this jungle thicket, my mindfulness becomes established …’ After appraisal, that mendicant should stay in that jungle thicket; they shouldn’t leave.
Take another case of a mendicant who lives close by a jungle thicket. Their mindfulness becomes established … And the necessities of life are easy to come by. That mendicant should reflect: ‘While living close by this jungle thicket, my mindfulness becomes established … And the necessities of life are easy to come by.’ That mendicant should stay in that jungle thicket for the rest of their life; they shouldn’t leave.
MN 17

Am I interpreting this correctly in saying that for an Arahant, it is forbidden for him to leave the place where he became enlightened?
Also, if so, how large is the area around this spot, where one can go to without breaking this rule?

user11278: There is no such requirement of staying in any place for an Arhant.
But the sutta you refer is specifically related to vanapattha paryaya (monastic practice). Where the Dhamma practitioner feels that s/his mindfulness becomes established, their mind becomes immersed in samādhi, their defilements comes to an end, it means the place is suitable and helpful for the person to arrive at Nirvana. Such places should not be left, as one needs every bit oh help that they can get in order to become an Arhant. If the surroundings are helping, such surroundings should not be left.
The sutta does not describe an Arhant, rather someone who is yet to obtain enlightenment.

23662: <blockquote>
<p>Take another case of a mendicant who lives close by a jungle thicket. As they do so, their mindfulness becomes established, their mind becomes immersed in samādhi, their defilements come to an end, and they arrive at the supreme sanctuary. But the necessities of life that a renunciate requires—robes, almsfood, lodgings, and medicines and supplies for the sick—are hard to come by. That mendicant should reflect:
‘While living close by this jungle thicket, my mindfulness becomes established … But the necessities of life are hard to come by. But I didn’t go forth from the lay life to homelessness for the sake of a robe, almsfood, lodgings, or medicines and supplies for the sick. Moreover, while living close by this jungle thicket, my mindfulness becomes established …’ After appraisal, that mendicant should stay in that jungle thicket; they shouldn’t leave.
Take another case of a mendicant who lives close by a jungle thicket. Their mindfulness becomes established … And the necessities of life are easy to come by. That mendicant should reflect: ‘While living close by this jungle thicket, my mindfulness becomes established … And the necessities of life are easy to come by.’ <strong>That mendicant should stay in that jungle thicket for the rest of their life; they shouldn’t leave.</strong><br />
<a href="https://suttacentral.net/mn17/en/sujato" rel="noreferrer">MN 17</a></p>
</blockquote>
<p>Am I interpreting this correctly in saying that for an Arahant, it is forbidden for him to leave the place where he became enlightened?</p>
<p>Also, if so, how large is the area around this spot, where one can go to without breaking this rule?</p>
 11278: <p>There is no such requirement of staying in any place for an Arhant.</p>
<p>But the sutta you refer is specifically related to vanapattha paryaya (monastic practice). Where the Dhamma practitioner feels that s/his mindfulness becomes established, their mind becomes immersed in samādhi, their defilements comes to an end, it means the place is suitable and helpful for the person to arrive at Nirvana. Such places should not be left, as one needs every bit oh help that they can get in order to become an Arhant. If the surroundings are helping, such surroundings should not be left.</p>
<p>The sutta does not describe an Arhant, rather someone who is yet to obtain enlightenment.</p>
