You are welcome to contribute any quotes/ knowledge regarding mysticism.

I'll share a few sayings by Shams of Tabriz. The Sufi Saint and mentor of Rumi.

Hell is in the here and now. So is heaven. Quit worrying about hell or dreaming about heaven, as they are both present inside this very moment. Every time we fall in love, we ascend to heaven. Every time we hate, envy or fight someone we tumble straight into the fires of hell. - Shams Tabriz

Nothing should stand between you and God. No imams, priests, rabbis or any other custodians of moral or religious leadership. Not spiritual masters and not even your faith. Believe in your values and your rules, but never lord them over others. If you keep breaking other peoples hearts, whatever religious duty you perform is no good. Stay away from all sorts of idolatry, for they will blur your vision. Let God and only God be your guide. Learn the Truth, my friend, but be careful not to make a fetish out of your truths. - Shams Tabriz

It is never too late to ask yourself, Am I ready to change the life I am living? Am I ready to change within? Even if a single day in your life is the same as the day before, it surely is a pity. At every moment and with each new breath, one should be renewed and renewed again. There is only one-way to be born into a new life: to die before death. - Shams Tabriz

A life without love is of no account. Dont ask yourself what kind of love you should seek, spiritual or material, divine or mundane, Eastern or Western. Divisions only lead to more divisions. Love has no labels, no definitions. It is what it is, pure and simple. Love is the water of life. And a lover is a soul of fire! The universe turns differently when fire loves water. - Shams Tabriz

The path to the Truth is a labour of the heart, not of the head. Make your heart your primary guide! Not your mind. Meet, challenge and ultimately prevail over your nafs (self, psyche, soul) with your heart. Knowing your ego will lead you to the knowledge of God. - Shams Tabriz

You can study God through everything and everyone in the universe, because God is not confined in a mosque, synagogue or church. But if you are still in need of knowing where exactly His abode is, there is only one place to look for him: in the heart of a true lover. - Shams Tabriz

Blessing is excess, so to speak, an excess of everything. Don't be content with being a faqih (religious scholar), say I want more more than being a Sufi (a mystic), more than being a mystic more than each thing that comes before you. - Shams Tabriz

Loneliness and solitude are two different things. When you are lonely, it is easy to delude yourself into believing that you are on the right path. Solitude is better for us, as it means being alone without feeling lonely. But eventually it is the best to find a person who will be your mirror. Remember only in another persons heart can you truly see yourself and the presence of God within you. - Shams Tabriz